1979 F100 Air Conditioning
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Air Conditioning

I'd wanted to put factory AC on this truck, so I was keeping an eye out for the right parts. First I found a mostly complete Deluxe Hi-Lo Heater system from a 1978 Bronco that I got cheap, and it's got much of the same firewall pieces as the AC setup, so that was the start on the conversion and helped me avoid running any of the EFI wires where the AC unit would (hopefully) go in the future. I eventually bought the shell of a 1977 F250 to get at the AC parts and the correct firewall hole so I could copy it onto my truck. I also got to snag a mostly complete AC setup from a 1973 F350 and take a number of photos of it as I was taking the pieces off so I could reference things later on.

 

Reference Photos

1978 Bronco

Below are a bunch of pictures of an AC setup on a 1978 Bronco - the guy who sold me the Deluxe Hi-Lo Heater setup had this truck around, but the AC system was already sold to someone else - but he was kind enough to let me take a bunch of pictures of the AC system. The firewall, dash, and core support areas are all functionally identical to my 1979 F100, so these pictures are a handy reference. Of particular note is the sheer size of the AC unit on the firewall, how close it comes to the passenger side of the motor, that the condenser mounts using the same bolts as the radiator, and the fact that there are 4 extra vents in the face of the dash for both the AC and Deluxe Hi-Lo Heater. The receiver/dryer mounts to the condenser out in front of the radiator, the fan is internal to the AC unit on the firewall, and there is a shutoff valve in the heater hose leading to the heater core. Also, the controls are partially vacuum operated, so you need hoses for that and a vacuum canister in the system somewhere. Knowing all this will help me figure out where to run the EFI wiring so that it's out of the way if I ever install AC.

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1976 F150

These are from a 1976 F150 with AC that I saw on eBay. It had good shots of the interior in it's intact/original form, and it shows the location of the vacuum canister in the first photo - it goes on the driver's side inner front fender.

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1973 F350

I tracked down this truck on Craigslist - the owner was parting it out due to a blown motor. All of the AC bits (save for the compressor, which I don't need) were still installed and intact, so I removed all of the relevant parts (except for the main AC/Heater case in the engine compartment), took a bunch of pictures, and made the seller a good deal on the parts.

Typical dash pictures. The controls were in nicer shape than the ones I got from the 1977 F250, which was good incentive to grab them, along with the related vacuum and electrical bits.

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Vacuum canister on the driver's side inner fender and the associated vacuum hookups. One connection on the canister (the one farthest from the engine, IIRC) is the vacuum feed form the engine, the other is the vacuum feed to the AC system. The vacuum lines enter the cab just inboard of the brake booster area. I will have to drill a hole for this on my cab, since there does not appear to be one there. The large vacuum line goes to the vacuum canister, the two smaller lines go to the heater control valve. It would appear the earlier style control valves operate a bit differently than the later style, since the later style is a single vacuum hose. That may affect the controls; we'll see how it all works out.

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The AC hoses and vacuum line routing across the firewall. Note the center metal clip holding things up and off the motor. The second photo shows the dual vacuum lines running to the heater control valve. At the top left of the second photo, just behind the braided metal grounding wire, you can see the barrel connector and the ground hookup for the blower motor. Later models used flat blade connectors, but the idea is the same - the blower power is routed to here, and on non-AC trucks goes right to the blower motor. On AC trucks, it is routed back inside the cab via the AC wiring (see below) and to the blower motor that is deep inside the AC/heater case. Also, you can see the insulation applied to the flat metal surface on the heater/AC case to help keep the cold air inside that way.

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Condenser and associated mounts and connections. Note that the accumulator to condenser hose has been replaced with a "custom" replacement (third photo) and will need to be replaced if I don't have a proper one from the 1977 F250. You can also see the way the accumulator mounts to the driver's side of the condenser and to the core support. The hard lines from the accumulator go over and through the grommet in the core support. There was a funky little wiring device there as well - some form of "too cold" sensor or something? I grabbed it in case it was needed since it appeared to be a part of the wiring for the AC compressor.

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The temperature control cable where it goes through the firewall above the main AC/heater case and where it connects to the bracket on the AC/heater case. You can also clearly see the heater control valve in the second picture, as well as the AC/heater case that is screwed together and not riveted like mine was. Judging by the presence of the funky looking goo/sealer on the edges, I'd say it had been disassembled and put back together with screws at some point in it's life.

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Another dash shot, this time of the passenger's side. Note the black painted areas and the blue painted areas. The trim is simply screws to the dash from behind, and the vents clip into the dash - they are a real pain to remove without breaking the clips...

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The driver's side air duct with metal bracket that holds it to the brake pedal support. The hose ends need to be carefully pried out of the metal clips to avoid tearing the ducting if you want to re-use it... I tore the end that attaches to the main plenum on the right. Oops.

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The inside of the vacuum grommet where it goes through the firewall. This one was a two-piece arrangement so you could disconnect the inner pieces for service of the stuff inside the cab. That's the white plastic cylinder to the right of the brake pedal brace in the middle of the picture. You just pull back on it firmly and it separates from the firewall piece.

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Here you can clearly see the main plenum with the resistor hookup to the right and the accordion style connection to the defroster duct to the left. One of the vacuum redirector valves (brass colored with vacuum connections on it) is front and center. You can just see one of the two mounting screws for the plenum cut off by the dash in the foreground; the second screw is already removed.

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The inside of where the temperature control cable comes through the firewall. It's a tight fit up close to the pinch weld - the inside air duct/case has a cut-out to make room for it. You can also see one of the mounting studs coming in from the engine compartment side. The inside just gets a nut to hold the inside plastic air ducting in place against the firewall.

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The fresh air/recirculate valve on the far right (passenger's) side. You can clearly see the temperature control cable hole, the accordion style connection to the fresh air intake on the passenger's side upper kick panel (along with two of it's three mounting bolts), and the long rod that extends down from the vacuum valve to the actual flapper door.

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This odd angle photo is looking up towards the underside of the fresh air/recirculate door. You can see the underside of the door and the rusty color flapper with the foam falling off of it, the control rod and the vacuum valve way up at the top. In the background is the accordion style connection to the fresh air intake on the passenger's side upper kick panel. Right now the system is in fresh air mode and the recirculate door is "down". When the door rotates up about 90 degrees, it closes off the fresh air supply and air going to the AC/heater system comes from inside the truck. For reference, the wire cutting across the picture goes up into the dash at the top right corner - the triangular piece of blue metal is the bottom lip of the dash where it meets with the passenger's side kick panel.

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The AC-specific wiring that connects to the factory blower wiring. The main power connections are the white bullet connectors (later models used flat blade style connectors). The blower switch is the three-prong connector with the white jumper in it. The red single wire connection goes to the resistor hookup - you can see the single open blade connection in the picture of the main plenum a bit higher on this page). The lone green (almost yellow-ish) wire with a white stripe goes to the anti-aice relay on the evaporator, see the next picture.

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Here you can see the wiring to the AC system. The orange + red + blue wiring bundle hanging down goes to the resistor in the main plenum. The green (almost yellow-ish) wire with the white stripe goes to the anti-ice relay, it's somewhat hidden by the grey and brown connector for the fan wiring. The fan wiring from the motor (orange and black) wires goes to the grey connector, the brown connector has the wiring that heads out into the engine compartment to connect to the blower motor feed out there. The purple wire that goes to the left connector on the anti-ice relay and goes out into the engine compartment is the feed wire to the AC compressor - when it has power, the compressor is on. Note the foam seal on the metal ridge to the left of the evaporator and to the left of the anti-ice relay. This seals the air in the inlet from leaking into the cab - in the winter that would be potentially ice cold outside air, so you don't want it dropping down onto the floor of the cab. Also note that the bolt on the left hand side are bolts running out towards the engine compartment to hold in the AC/heater case. One is half way cut off in the bottom middle of the picture, just tot he left of the green wire with the white stripe.

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The lower section of the evaporator. Note the debris here - sticks, needles, moss, etc. - the air inlet does a good job of funneling crap to this spot where it sits for years and years. Good thing the evaporator is aluminum and won't rot out, too bad the cover plate to the left of that foam is steel and does rot out over time... Also, note the studs on the bottom that protrude into the passenger compartment. These serve to mount the inlet plenum via nuts. The one to the bottom left was covered with a piece of rubber to prevent tearing the passenger's shoes, the floor mats, etc..

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The upper section of the evaporator. Note the hole in the firewall for the temperature control cable, the two mounting studs protruding into the passenger compartment (top left and right), and the nut on the stud to the left that holds the main AC/heater case to the firewall. There is a second nut on the once the air inlet/plenum is mounted in place - the plenum is sandwiched between the two nuts. You can also see that there is a foam seal to the right of the evaporator as well as the left. More of an air seal around this plenum is a very good thing since unconditioned (aka, unheated or uncooled) outside air will be inside of it much of the time.

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Another shot of the inside wiring and of the two lower inside mounting bolts. See that warpage in the side of the AC case? That should have been a hint...

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A close-up of the wiring for the blower motor where the AC blower wiring hooks up to the non-AC wiring harness (the bullet connector is disconnected), it's grounding connection above the pinch weld, and the grounding strap that goes into the pinch weld.

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The main hole in the firewall. Note how close it comes to the pinch weld and to the inner fender on the bottom. This is a gargantuan hole in the firewall!

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This is the underside of the AC/heater case where it was next to the exhaust. Oops. Apparently, there was an exhaust leak spewing a jet of red hot exhaust gas onto the case in this area and it basically just melted and blew the partially melted pieces of the case away from the motor. The 390 exhaust manifold has it's joint right next to the case, instead of back further and down lower out of the way. The bolts got loose, and a small gap opened up, creating a searing hot spray of still burning fuel. The thing to remember is that this picture was taken with the case upside down, so areas where the case appears to have melted down, actually melted up! That means the hot exhaust was blowing onto the case with enough heat and force to not only melt it, but as it softened up, to push the softened sections of the AC/heater case up and away from the motor. Impressive. Also impressive is the direct leak of exhaust fumes into the cab due to this. With the fan on (if it worked) it would have been spewing exhaust right into the heater system and into the cab. Not good. You'd think the driver would have noticed and thought "gee, I really need to fix that exhaust leak that's making me sick to my stomach and lightheaded while I drive the truck"...

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The data plate from the driver's side door pillar confirming this was a very early build 1973 truck, November 1972 to be exact. It also had an impressive 6310 lb rear axle capacity - this thing was set up to haul a serious load. The blue overspray indicates this truck had a quick re-spray earlier in it's life that didn't do the door jambs. Also interesting is that none of the detailed info at the bottom of the tag is filled in. The VIN of F35HRQ68356 decodes to F35 = F350, H = 390 2bbl V8, R = built in Jan Jose, CA, and Q68356 is the serial number of this truck. Yeah, I'm a data plate geek. Knowing that the info checks out with what I was told about the truck confirms details about the AC setup as being most likely authentic.

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AC System Rebuild

This section details the rebuilding of the AC and heater box that I'm using out of the 1977 F250 - I took lots of photos so I can figure out how to put it all back together again later. :-) It also details (or, will once I get that far) the installation of the AC system into the truck.

 

The AC hose connections and the wiring harness for the engine compartment side of things. This has a ground and a connection to power at the solenoid.

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More of the AC hose connections. This details how the temperature control valve bulb is mounted to the larger tube/hose section so it can sense the temperature of the hose. I think the larger one is the outlet hose, the idea being that if the outlet hose gets too cold, the evaporator is close to freeze up, so they need to shut off the flow for a bit. This whole section gets covered in cork insulating tape.

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Here's the wiring on the inside, it shows where the orange wire comes in from the engine compartment (lower left grommet), the anti-icing relay connections (with the sensing bulb in the evaporator fins), and the wiring going into the unit (upper middle grommet) to the blower motor.

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Another view of the temperature control valve mounting so I can get it put back together properly later on.

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The AC hoses that come off the evaporator, and a shot of the engine compartment AC wiring harness after being removed from the unit.

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The AC hoses where they go into the evaporator, the second shot shows the placement of the grommet underneath the metal cover.

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Wiring to the blower and the upper mounting screw for the evaporator.

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Anti-icing relay mounting, plus where the lower mounting screw for the evaporator should have been (but wasn't). The second pic clearly shows the relay mounting orientation by the whitish area of dirt. I believe this gets pretty cold, and will tend to have condensation on it, thus will collect pollen and dirt.

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The cover plate the the anti-icing relay mounts to and that the blower wiring grommet goes into has been removed, and you can clearly see the edge of the evaporator that goes behind the cover plate, plus the routing of the tubing, and the two grommets that the evaporator tubing passes through.

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A shot from the bottom where I found another missing evaporator mounting screw...

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Wiggling the evaporator out of the housing. The outer grommet has been fully removed (it has slits in it to allow it to bend over the tubing), and the inner grommet is being slid out of it's mounting location.

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The evaporator, in all it's $300-brand-new-price glory. Yes, you read that right. I found one source for it, and it's about $300. Ouch. Don't drop it, and hope it's not plugged...

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The inner grommet with it's slots to go over the evaporator tubing. I could not find these new, so don't mess it up!

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The case, minus the evaporator. Heater core is on the left, the temperature blend door is on the left - there's not much airflow space in there for the AC when it's in full AC mode, is there?

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The heater core mounting straps, proper upper/lower positioning locations relative to the previous picture.

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Heater core minus mounting straps.

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That little screw way in the back lower left corner of the case and it's little tiny mounting clip are what hold the bottom of the main control rod for the temperature door in place. The other end of that control rod is what pokes up out of the case and is connected to the Bowden wire that goes to the temperature control lever on the dash. You can see part of the other rod inside the housing - there are two of them on the temperature control door, and the door should pivot inside the housing on both of rods at the same time, forcing the door to change angles in some pretty funky ways. You have to see it to understand it. Also, note that I did this step out of order - I didn't have to remove this to remove the heater core in the next step.

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Here's the heater core, and it's foam rubber surrounding/mounting piece. With the foam well stuck in place from years of moisture and setting there inside the housing, it was a real pain to remove. Go slow, push gently on the exposed heater core tubes (I tried to hammer on mine, and tweaked them a bit), and it will eventually wiggle it's way out of the housing. The foam is just sitting on the heater core, and stuck to it from years of compression and heat cycles. It will come off if you are careful. I got mine off in one piece with zero tearing. It needs a good cleaning, and thorough drying, but it should be fine to re-use, unless I can find a new one somewhere.

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Here's an upside-sown picture of the housing taken from the engine side. The foil insulation helps reject heat and keep the cold air stream cold when the AC is on. This ends up pretty close to the exhaust and the engine, after all...

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More foil on the bottom of the final air ducting parts.

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Here's the temperature control door after it's been unsnapped from it's two control rods. It's tight and was a bit rusted on from years of use, but it will snap off if you're careful. Note the three simple metal snap clips in the first picture. I may need to re-apply the foam on this to make it all work right - the existing foam is pretty brittle from age and years of heat cycles.

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The blower wiring where is goes between the "cage" the mounts the temperature control door and the housing. Note the pre-formed flat rubber grommet molded onto the wire.

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A close-up shot of the grommet and the wiring going to the blower motor, as well as the two mounting screws for the cage. Note the slightly raised section of the "cage" to fit over the grommet. The first photos shows the right mounting screw (actually, lower, when the housing is in the correct orientation), the second photo shows the left/upper mounting screw. Don't confuse the blower motor mounting screw second photograph for the cage mounting screw. The blower mount screw is higher in the photograph, and has a small cut-out around it in the "cage".

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The temperature control door "cage" after being removed. You can see one of the two control rods laying flat inside the cage.

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The housing, minus the temperature control door "cage". You can clearly see the control rod behind the motor, minus it's mount to the lower right. Removing that lower right hand screw should have been done here. You can also clearly see the foam under the mounting cage, the flat grommet for the blower motor wiring, and how the blow motor is mounted to draw air across the motor, and into the output part of the housing, and then back into the passenger compartment. Because the blower motor is always in the airstream created by the blower when it's running, it's self-cooling, although this will impart some heat to the airstream in AC mode - not ideal, but it'll work.

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More pics of the temperature control door "cage". They are both upside down and viewed from the back so you can clearly see the second control rod hanging down. You can also clearly see the notched area that fits over the flat rubber grommet for the blower motor wiring. This will need to be extensively cleaned and painted to prevent rust, and the control rod still needs to operate freely when it's done. The control rod can be carefully removed by bending the legs inward, just don't permanently bend it out of shape by acting like a gorilla. The cage itself is also fairly delicate (especially due to rust in some areas) and has some sharp edges, so be careful with it. Your tetanus shots are up to date, right? :-)

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This is the main temperature door control rod once removed from the main plastic housing. You have to carefully remove the plastic bushing from the housing, while it's still on the control rod. These are brittle and break easily, so be careful. I don't know of any replacements available for them. This will need to be cleaned and sealed somehow before the housing is re-assembled and installed in the truck.

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Here's the blower motor and it's mounting bracket. In the first shot you can clearly see the foam that goes over the flat rubber grommet for the wiring and under the temperature control door cage. This helps seal that area from air leaks, and prevent rattling. I will need to replace this with new foam during the rebuild, it will have to be custom cut from a sheet of comparable material.

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Attempted close-up shots of the mounting set screen for the blower wheel. You have to reach in between the vanes with a long Allen key to remove it.

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The final housing once everything is stripped from it. The rust stains need to be cleaned up, but you need to b careful of the soft insulating/soundproofing material on the inside of the metal cover on the engine compartment side of the housing. I don't know how this will fare with cleaning, so I'm going to be careful. I will also need to somehow strip and refinish the paint on the metal part of the housing.

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Here's the firewall after everything has been moved out of the way. I found I had to unbolt the passenger's side of the smog crossover tube and push it down an inch or so to gain the required clearance. I also had interference issues with the throttle body while trying to install the housing; I may need to remove that temporarily when I do the final install - the amount of bending and pushing I had to do on the empty housing to get it under the upper firewall lip and against the firewall made me...uncomfortable.

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Here's a few pictures of the poster board template I made from the firewall of the 1977 F250 parts truck. I cut it to fit against the various surrounding pieces, and then cut out the center section, and made holes for the mounting spots. I checked it by making a matching plywood template out of 1/2" plywood, but I could not use that to fit onto this truck due to the fender and engine being in the way to get it in place.

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I taped the poster board template to the firewall and shot it with a quick coat of white paint to outline the needed cut points on the firewall. Also, compare the second shot to the similar one up above and see how much lower the smog tube is now that it's been unbolted and pushed out of the way.

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The original blower motor and wheel after I was finally able to separate the blower wheel from the motor. They are a tight fit on the shaft to begin with, and years of mild corrosion had almost welded them together. After a liberal dose of Kroil and liberal application of direct heat from a propane soldering torch, I was eventually able to pry and pound it off the blower motor shaft - yes, pound. It was not a pleasant experience. You can see the results of the pounding on the underside of the center piece on the wheel - it's not pretty. I had to run a round file through the center hole to ensure there were no burrs or sharp edges that would cause it to get hung up on the shaft on the new blower motor. All in all it took a few hours of work to remove, but I got it off without tweaking the blower wheel too much. They're not available new for the AC setup; the only one I could find was for a non-AC setup, and unfortunately it's not the same. The non-AC wheel is much smaller in diameter and shorter. It looked positively comical when set on the AC motor - I regret that I did not take a photo as a comparison. The blower wheel will be de-rusted and painted with a rust-proofing paint to preserve it. I may also need to tweak a few of the fins back into shape - the screwdrivers I used to pry it off were slightly bigger than the opening between the fins and I was doing a lot of prying...

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Here's the new blower motor and heater control valve. The blower motor has the right mounting cage, but the wiring is just stubs that need to be spliced into wires cut form the original motor. I was hoping not to have to do that, but such is life. The heater control valve is labeled for flow direction (see the arrow in the close-up), and just sort of hangs inline with the heater hoses. Run the proper vacuum line to it, and you're pretty much done.

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Here's the new heater core, which came pre-bent, thank you very much UPS. It's a pretty good match, but the original thick foam padding that surrounded the original heater core won't fit the new one - the end tanks are not the same shape (they're a bit larger in all dimensions) and there are raised areas near the pipe connections that protrude through the AC/heater case. I'll have to rig something custom up to help hold it into place and seal it to prevent airflow around it.

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Here's the custom foam material I bought to try and make new case-to-firewall gaskets out of, since I can't find them being reproduced. It's about the same thickness as the original material, but not quite as dense. I got these at a local fabric store. The two big pieces are "headliner" material in different colors with a thin layer of foam pre-attached to them. I don't really care about the colors (though I did choose something ark so it won't be seen easily), but they had different densities of foam attached to them, so I grabbed them both. The smaller green foam may be useful in various ways (around the heater core?) so I grabbed that as well.

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Here's a couple of photos of the spare AC/heater housing I have that show the position of the insulating blanket on the outside of the unit and of the orientation of the metal bracket that holds the end of the temperature control cable.

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I bought some Rust Dissolver from Eastwood and will be trying that on the metal bits to de-rust them, including what's riveted to the plastic AC/heater housing and the inside metal pieces. I got a large Rubbermaid tub to sit the housing in, and as per the instructions on Eastwood's website, a small fountain pump to continuously spread the Rust Dissolver over the needed areas. The entire housing is simply too big to submerge and the Rust Dissolver is not cheap at $30-$40 a gallon, plus shipping. I got 2 gallons on sale for a good deal. The Rust Dissolver is supposed to be safe for plastics, which makes it perfect for my needs. I can coat the de-rusted metal with one of Eastwood's coatings to preserve it. In this case, I selected their Underhood Black for the semi-gloss finish since the metal on the outside of the housing will be visible in the engine compartment. The pump does an acceptable job, but submersing the parts is far better. The plastic was untouched and the attached metal clips for the screws came out looking pretty good. Since my parts were in pretty bad shape in places, and I was working on this as I had time, I typically left parts in the Rust Dissolver bath for days at a time. When I pulled them out, I did a final cleaning of the parts with the garden hose and some vigorous scrubbing with a small metal bristled brush. It worked well, though it did require some elbow grease in places.

This is my first attempt at the plastic housing with the metal side cover and metal temperature cable bracket still attached. This is the entire thing in the plastic tub using the fountain pump to recirculate the Rust Dissolver over the important areas.

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It sort of worked, but not well enough - I needed to get into cracks and crevices with a wire brush to ensure they came out as clean as possible, and repainting the metal parts to prevent more rust form coming back was going to be a problem with it still attached. You can see the rust on the front and back side of the rivets in the last two photos. How do you paint that properly? Exactly.

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Drilling out the rivets attaching the temperature cable bracket and the side cover freed them up pretty easily. The inside of the side cover was more intricate than I'd first thought (it had insulation, a retaining metal grid behind three metal fingers, and a rubber gasket to seal it) and the inside was much dirtier than I'd thought. Separating out the insulation from the metal retaining grid allowed me to clean them separately. The rubber gasket was peeled off using a razor blade. I'll have to replace this with something custom later on when I re-assemble the housing.

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Here's the new blower motor with the de-rusted and re-painted blower wheel installed on it. I was able to transfer the rubber grommet to the wires on the new motor by carefully slitting it down the back side, removing it from the original wires, and inserting the new wires into the slit. I then used some Elmer's glue to seal up the slit so nothing would fall out. Once it's installed the grommet and wires are held in place by compression and it won't be going anywhere, so the glue just helps with re-assembly of everything into the case. The reddish paint is the color I bought of Eastwood's Rust Converter. For stuff that won't be seen, I'm just painting it with that to seal the parts and keep them rust free. For things that will be seen, I'm top-coating the Rust Converter with Underhood Black.

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Here's the case after a thorough scrubbing with a scotch bright pad, some dish soap, water from the garden hose, and lots of elbow grease. I think it came out pretty darned good. Before scrubbing, I pulled all the insulation off by pulling all of the metal staples out - they were rusty, falling out in places, and were a serious hazard to my hands as I scrubbed. I'll replace this with something else when I put it back together. There are various kinds of stick on insulation sheets. Also, there were stables in more places than there were insulation, leading me to believe that there might have been more insulation on the case at one point in time. This would make sense - more insulation would help keep the case cool when the AC is being used, which would mean colder AC outlet temps inside the truck. Why bother cooling the air only to have the engine heat warm it right back up again through the case? That makes no sense. Insulation on the outside of the plastic AC/heater housing is a cheap way to solve that.

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Here's the restored temperature control door "cage" with the control level rod installed into it, ready to have a foam gasket added and get installed into the plastic AC/heater housing.

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Here's the restored side cover with the insulation and insulation retaining grid re-installed into it, ready to have a foam gasket added and get installed onto the plastic AC/heater housing.

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These are the replacement screws I bought to mount things into the plastic AC/heater housing. The originals were all #10 x 1/2" long screws (or sufficiently close enough to be indistinguishable), but to make mounting some things easier (like the fan and the temperature control door "cage"), I bought #10 x 3/4" long screws. This will make it easier to get screws started with thicket foam gaskets in places, and since there is nothing behind them to interfere with, it works fine. Anything that goes into a blind hole in the case needs to stay with the original 1/2" length screw, though.

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Here's the blower motor mounted into the case. I temporarily installed all four screws so I could test the motor by hooking it up to a battery - wow does it move a lot of air, even with the side cover off! Note that after testing the motor, I had to remove the right front screw in the first picture so I could do more assembly work. Why? The temperature control door "cage" mounts using this screw, so it has to go in after the cage is in place. I found this out by trial and "oh, yeah"...

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Here's the foam gasket on the bottom of the temperature control door "cage". This is 1 1/4" wide x 1/2" thick foam weather stripping I got at Home Depot. It's a bit thick, but it was what they had in the right width. I later found some camper shell mounting weather stripping that's much thinner (about 1/8"), but this worked for me. I used the sticky side to attach it to the "cage" and then trimmed it to fit where needed with a razor knife. See the right side piece in the first picture. The left side piece in that picture was what I trimmed off, so I stuck it there to give a good seal all around. This is what keeps cold air from leaking around the heater core when you want warm, de-humidified air to the defroster. As long as you can get the cage in place, and the pieces of foam fit together decently, you should be fine.

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I opted to grease the temperature control rod where it sits in the "cage". A bit of lithium grease on a toothpick was easy to apply without making a mess.

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I also greased the main temperature control rod, both inside the plastic bushing at the top of the case and where it will sit in a groove in the housing ad be retained by a small metal clip that gets bolted into the housing. It will be easier to install and bolt this in now, before the temperature control cage is installed.

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For easy visual reference, here's a picture of the screw I had to remove from the blower motor mounting so I could install the temperature control cage.

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Here's the small metal retaining clip that holds in the main temperature control rod. This gets one of the shorter screws (#10 x 1/2") since it goes into a blind hole in the plastic AC/heater case.

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Here's the temperature control cable bracket freshly riveted onto the case. The rivets were 3/16" diameter and had a clamping range of 1/8". I had to drill out one of the bracket mounting holes slightly due to paint buildup. Other than that, it worked perfectly.

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Here's the rivets from the inside of the case. It was tough to get a good shot that was well exposed and not over-flashed on the rivet, but between them you can get the idea. The rivets were slightly taller then the originals, but it everything fit - barely.

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Here's the temperature control door cage installed and screwed into place. Due to the taller rivets it was a tight fit. I needed to position the rod inside cage towards the firewall side (closest to the camera), slide the cage in place with the temperature control door roughly in place, and then snap the rod into the clip on the door. It was a tight fit, but it worked. After it was snapped in place, it took some wiggling to get the cage properly seated. It was bolted down with two of the longer screws (#10 x 3/4") - the one on the left goes into the case, but it's not a blind hole (aka, it's drilled all the way through).

The door moves such that when it's in "cold" mode it sits parallel with the top of the cage and all the way against the front of the case (away from the camera) - the seal is against the case and the top of the cage. Air flows in through the open area at the front of the cage, bypassing the heater core. The heater core sits on the top section of the cage. When the door is in "hot" mode, it moves towards the camera such that the leading edge moves down to seal against the bottom of the cage and the far side seals against the top of the cage. The allows air from "behind" the heater core to go around the cage and into the fan. Once properly cleaned and lubricated, the door works very smoothly - I had trouble getting it to stay up for the picture...

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Here's the side cover riveted back onto the case. I used thin stick on weather stripping (the kind used to seal a camper shell to the bed of a pickup) to seal it to the case. I stuck it to the metal cover and trimmed the outside edge to fit. Due to the curve, I ended up using a lot of smaller pieces to get a complete seal, all cut to fit snugly against each other with a razor blade. I cut the holes from the gasket side using a 3/6" gasket hole punch. I just compressed the gasket until I could feel the hole through the gasket, and using my finger underneath to feel what was going on, I pressed the gasket hole punch in place and twisted it to make the holes. It was a very good result, and since I was careful with my finder underneath, I didn't even get a scratch. The rivets needed to be a bit longer than on the bracket due to the gasket - 3/16" diameter by 1/4" clamping range. I used rivet washers on the back side to keep them from pulling through the slightly larger holes in the plastic case. I didn't on the first one, and it was not a happy thing. Also, the rivet stems snapped off half way up in a few cases, so I had to use side cutters to cut off the stems as flush as possible with the rivet heads. It's not perfect, but it's pretty good. I'm thinking that I should have pre-compressed the gasket and maybe used the 1/8" clamping range rivets; live and learn, I guess...

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Here's the custom foam I put around the replacement heater core to keep it in place and keep it from rattling around and wearing holes in things that shouldn't have holes. The original heater core had smaller end tanks, and the spiffy factory foam rubber piece wouldn't fit onto the replacement heater core. Cutting the holes in the pieces to go around the tubes was interesting. I pressed the tubes into the foam pieces to make marks, and then cut them out as best I could. It's not perfect, but it should work.

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The wedge shaped piece along the side of the heater core was the only piece of the factory foam rubber that I could use. Even then, I had to cut it out of the larger piece.

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Here's the heater core nestled in place with the wedge shaped foam piece on the side helping hold things in place. From the outsude of the case, you can see a bit of the grey foam, but not much. The heater hoses should cover this up.

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Here's the mounting straps in place. Because the original heater core uses smaller end tanks, the straps are not really seated properly and are a bit bent to fit, but they should work. The bottom one (first photo) used the shorter screws (#10 x 1/2") in blind holes - I was able to angle it around a bit and get the screws started without much of a problem. The top strap (second photo) used the longer screw (#10 x 3/4") - I couldn't get it started otherwise. I did have to be careful not to over tighten the top mounting screw, though.

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Test fitting the middle spacer/shield piece that the wiring goes through. Short screws (#10 x 1/2") were used on the left edge to mount it so they wouldn't stick out too far.

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Here's the wiring to the new blower motor spliced into a section of wiring from the old motor. Each wire was crimped with metal connectors, then soldered, then heat shrink tubing was applied. Don't forget to slide the heat shrink tubing over the wires before you crimp...

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The final spacer/shield mounting with the wiring fully taped up and the wiring grommet in place. I wrapped the positive connection with a layer of fabric tape to prevent any inadvertent shorts from any errant sharp edges on the soldering, then I wrapped the whole section of both wires with non-sticky vinyl harness tape with a small section of fabric tape at the end to keep the vinyl from unwrapping. It ended up a bit longer than I wanted, but it should be fine. I tested the blower before the final harness wrap, and both it and the temperature control door work great. This thing moves a lot of air!

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I cleaned the rubber seals for the AC evaporator tubes using warm water, Simple Green, and a few soft bristle brushes (old toothbrushes on up to slightly stiffer nylon brushes). The caked on grime came off pretty well with a few rounds of scrubbing and rinsing. The seals themselves are pretty stiff and old, but should still be serviceable/usable for my needs. I can't find reproductions anyway, so I need to use what I have available. I set them aside until I could get the evaporator tested so I knew if it would work right. No sense installing it now if it's not going to work right later on, right?

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Here's the evaporator after testing (no leaks - woo-hoh!) and after some quality time with a fin rake and a pair of small screwdrivers. The fins are much straighter now and should result in much better airflow through the unit. The #14 rake worked perfectly, though it took some time to figure out which one was right due to how much damage there was all over the unit. This was my first time using the fin rake, and it took some getting used to, especially where the fins were severely bent over each other and smashed down. The thin metal stretches and tears easily. You have to gently get the fin rake in place and not bend any of the fins when inserting it. Then gently pull and wiggle it along to straighten that set of fins. Repeat for tough bends. Move on to the next section. Overlapping 2-3 fins on each pull helped keep things aligned overall. I had to use small screwdrivers to straighten fins near the raise edges on the front "firewall facing" surface. The raised aluminum bits got in the way of the sides of the fin rake. After this I blew the dust and pine needles out with compressed air - a surprising amount of dust and junk came out during the fin straightening process, and even more came out when I applied compressed air.

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Here's the evaporator installed and fully screwed down. It was a really tight fit to wiggle into the case - the top and bottom fins were touching the case the whole time, and it was a bit of a challenge not to bend them up after just straightening them. The rubber gasket in the middle of the tubes should go onto the tubes first, and then get wiggled into place s you angle the evaporator into the case. Don't forget to pull the wiring out around the edge as you install the evaporator - it's impossible to pull out after the evaporator is installed. I had to gently straighten the left mounting edge with a pair of lineman's pliers - it had been tweaked a bit previously and was not lining up properly with everything around it. The top left mounting tab is intentionally set at a strange angle to match that section of the case - don't try to make it flat like the other three mounting tabs. The bottom right screw needed to be one of the longer ones (#10 x 3/4") - there was a small air gap there and the longer screw was needed to get it started with pushing on the case too hard. The spacer/cover plate goes in last and in my case was a really tight fit - it sort of popped into place with a few taps from my fingers. Don't tighten the mounting screws until they are all started - I learned this, and several other "don't do this" tips the hard way. :-) After all that, the anti-icing relay sensor tube needed to be carefully bent back into shape to allow me to prepare to mount it to the spacer plate. Unfortunately, I ran out of the short screws (#10 x 1/2") at this point - apparently I needed to buy more than I originally thought I did. Oh well; one more visit to the hardware store - with the cost of gas, these are some pricey mounting screws...

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Here's the side cover plate and gasket mounted in place. I forgot about the gasket until the evaporator was fully installed - an annoying but solvable mistake. I managed to wiggle it in from the back and bend it enough to get it through the opening, but it was a real struggle. The rubber is not as pliable as when it was new, and I had to be careful not the shatter the gasket into pieces. Ideally, this gasket would have been been installed when I first started installing the evaporator - poke the evaporator tubes through the big hole, install the outer gasket, and then get the evaporator and spacer piece into place and screwed down. Live and learn, I guess.

The cover plate shows a speckling of red Rust Converter because it was laying on the bench when I painted something else, and the overspray carried further than I thought it did. It's easy to remove and touch up as soon as I get a chance. Also, why only one screw? Because I ran out of short ones, and I only had one long screw (#10 x 3/4") left to get this temporarily put in place the night I did this work. I'll replace it with a short one and add the missing one, as soon as I get more short screws (#10 x 1/2").

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Here's the cover with the final screws installed. It turns out the longer (#10 x 3/4") screws are needed here. The shorter (#10 x 1/2") screws didn't get through the gasket and grab the metal clips properly. And, the bag of #10 x 3/4" screws I bought were slightly different in head size than the others, so I replaced both of these with the new ones so they'd match and not confuse me later. Same manufacturer, same store, same size, different screws. Go figure.

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The anti-icing relay is now bolted down using the shorter (#10 x 1/2") screws I bought. That was easy. I do need to see about plugging the hole in the plate that gets used for a wiring clip, or possibly actually using a wiring clip here to hold the wiring in place. :-)

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Page last updated 04/26/2010 08:01:52 PM