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Old 03-16-2013, 04:20 PM   #1
Rivet Master
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1974 20' Argosy 20
Richmond , Kentucky
Join Date: Jan 2003
Posts: 5,133
1974 Argosy MH dash A/C rebuild

As many of know I've been tearing into the Argosy dash trying to get the dash A/C components removed so I can refurbish and repair various pieces and parts. Rather than put this in my restoration thread I thought it might be easier for future Argosy owners to find if it had it's own thread.

A lot of what I've managed to get done so far is due to the efforts of John (Shepherd57) and the fact that he has already been down this path and has been more than willing to share what he learned along the way. Once I knew the dash A/C system could be removed it made it easier for me to keep plugging away knowing that it could be done.

There were several reasons why I felt removing the A/C components was necessary. A couple of which can be seen in the pictures below. The air ducts were filled with mud dauber nests and the drain pipes from the evaporator box were plugged and because of the plugged drains there was a hinged fresh air door on the outside lower front edge of the evaporator box that was frozen part way open.

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The following picture shows the A/C components that need to be removed. The system is made up of the evaporator box and the air plenum.

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Now, to get the A/C components out of the dash you literally have to tear the entire dash top off and the front of the evaporator box as well. It also helps if the front of your motorhome has been removed as well. I'm not sure how easy it would be to get the evaporator box out if you only had the hood opening to work through. I've detailed most of the dash removal work in the following thread: 74 Argosy 20 motorhome restoration rebuild

Tearing into the dash is not for the timid There were several times when I almost regretted tearing into it but after having seen what the inside of the evaporator box was like I'm glad I did.

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The order of removal does make a difference. Preferably the evaporator box is removed first and then the air plenum. Doing it in reverse order (like I did) is more difficult, which unfortunately is my normal way of doing things Had I taken the time to think about it first I would have done it in the preferred order

Before you can get to the screws holding the evaporator box in place you have to remove the plastic cover. The cover is held in place by four screws along the bottom edge and four screws along the side. Once the screws are removed the cover should come out relatively easily. There is a piece of insultion behind the cover that you will want to save for re-use.

Mine did have a battery control switch that was held in place by a couple of screws. I'm removing that switch for good and will be using a different means of managing the batteries.

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The evaporator box is attached with 10 sheet metal screws from the inside of the cab. Four along the top and three on each lower corner. Plus there is one sheet metal screw that has to be removed from the drivers side of the evaporator box where a sheet metal divider plate is fastened, just above the expansion valve. This last screw is accessible from the engine compartment. The box edges were sealed on the outside with a tar type substance that is messy to work with. Keep in mind once those eleven screws are removed the evaporator box is going to drop like a rock!

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While it is advisable to have someone assist in removing the evaporator box I managed to remove it by myself. I used a 2x4 wedged between the frame and the bottom of the evaporator box to hold it in place while I removed the 10 + 1 screws. It wasn't quite as heavy as I expected but you have to be careful when removing it due to the heater core pipes and the evaporator core pipes sticking out the drivers side. I was able to just pick the box up a little and let the 2x4 fall out of the way and then lifted the box out the front.

To be continued...

Air forums # 1674
1974 20' Argosy Motor Home
1974 31' Excella trailer (parting out, as of 4/1/2015 I have wheels, brake drums, windows & holding tanks left to sell)
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Old 03-16-2013, 04:47 PM   #2
Rivet Master
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1974 20' Argosy 20
Richmond , Kentucky
Join Date: Jan 2003
Posts: 5,133 too tear into the evaporator box to see just how bad things are.

There are five or six sheet metal screws that hold a cover plate covering the blower motors and the evaporator and heater cores. Things didn't look to bad from the initial view inside this area although what looks like dog or cat hair is present in small quantities I was hoping that wasn't a sign of things to come...

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To get access to the cores and the bottom doors (fresh air and return air) you have to remove five screws. Once those screws are removed the bottom section can be removed by gently tapping around the edges with a punch. Once the bottom is removed this is what I found

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The evaporator intake side is coated with pet hair and wasp nexts. There has to be at least 40% blockage of the cooling fins. Not good. To get the evaporator and heater cores out there are four screws on each side that have to be removed. Once the screws are removed the evaporator core pretty much slides out. As you can see the pet hair has made it all the way through the evaporator and is partially blocking the heater core.

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Once the cores were removed that left just the blower motors inside the housing which looked relatively clean. Other than testing the blowers to make sure they run I shouldn't have to do much to the inside of the box.

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Now the bottom section which doubles as the drip pan for the evaporator is a different story. The engineers that designed the evaporator box apparently assumed the drains would never plug, yeah right! Unfortunately once they plugged the hinge for the fresh air intake was sitting in water. The hinge is now frozen in place. A bit of good news is it appears both vacuum servo actuators seem to be in working condition. I'll test them in the next day or so to make sure.

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Fortunately the return air door hinge which is also made of steel was at the high end of the bottom section so it didn't get as wet. I was able to get it to open and close after working with it for a while.

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I will likely replace the fresh air door hinge with a section of stainless hinge. I was hoping all I would have to do to the evaporator box was clean things up and re-install but that wasn't to be

Next up will be tearing into the air plenum and I'll post more pictures of the repair work on the fresh air door hinge.

Air forums # 1674
1974 20' Argosy Motor Home
1974 31' Excella trailer (parting out, as of 4/1/2015 I have wheels, brake drums, windows & holding tanks left to sell)
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