The AC/Heating (HVAC) system used from ’76-79 (F and M-body) is completely different than the HVAC system used from ’80-89 (FMJ).
Also, the no-A/C is completely different from A/C versions. I can’t comment about the differences between standard no-A/C versions vs Bi-Level no-A/C versions, for don’t think I recall working on a Bi-Level no-A/C system before. The no-A/C versions are not the issue at hand, here.
Let’s try to avoid comparing ’76-79 HVAC versions to the ’80-89 versions. The firewall components and rearward are mostly different
Next – that green vacuum hose block tends to crumble – even when cars were somewhat new. In early ‘80’s, the front wheel drive (FWD) cars got reformulated green plastic that holds up a lot better. I had a friend that had an ‘80’s Caravan and stole all the under-dash HVAC hoses and moved it to his Diplomat and it worked fine. I would think it might have needed some stretching (ie: hoses cut and lengthened) – but I didn’t ask any specific questions. For whatever reason, All FMJ’s got the crappy plastic 7-way vacuum connector that crumbles when someone blinks their eyes 10-feet away.
Also, the ‘80’s Caravans use a 7-way vacuum hose extension that has the male and female 7-way connector (with the good green connectors) that if a person wanted to retain the “connection”, you can cut that foot-long extension in half, then use vacuum hose to splice both ends to your existing harness.
Honestly – the easiest and best way, is to just clean off the “crumbled connector” parts from existing vacuum lines and use a short piece of rubber vacuum hose and splice the existing hoses, color to color, as mentioned above. Most of us will rarely need to disconnect your splice – and if you do, it’s not hard to get them back correct, again.
ON A DIFFERENT NOTE: the two vacuum tubes that go through the firewall, the “black” and “gray” tubes, tend to break when man-handled. When this happens to the black tube, you will not have any vacuum to work any of the vacuum controls inside the cabin. The black tube connects to the vacuum tree on intake manifold. This is a picture from my ’86 Fifth Ave 318 2-bbl.
If the gray tube cracks (or gets disconnected and not reconnected), then the hot water valve is inoperative. This is a picture from a fellow forum members car.
The green circle is the hot water valve (used on A/C cars (either normal or SATC), only). The gray hose is marked by red arrows (for proper routing). There is a firewall grommet the gray and black hose share, is located in about the area of the orange circle.
I would guess that most of our members street driven cars – either or both hoses have at least one crack in the plastic tube(s) – but it is easy to fix using a short piece of vacuum hose (might have to take a piece of tube to auto parts store to get correct size).
Generally, the underhood tubes and the green 7-way connector is where 99.5% of all A/C vacuum related problems are at. The other vacuum components do not five much problems, in my opinion.
The SATC motor hasn’t been available from Chrysler for a long time and I hadn’t found anyone who fixes them. I have (or had) a box of about 15 bad SATC motors, in hopes of fixing a few of ‘em – but hadn’t seen or ran across that box in a long time.
In my opinion, if you have an inoperative SATC system, the best fix is to change it over to a conventional A/C system. The two A/C control heads are slightly different (conventional uses a cable that connects to the top A/C lever, whereas SATC uses an electrical sensor connected to the control head lever) – but it is not hard to obtain an older control head (or get one from a ‘80’s Dodge pickup, etc.) or get a lever and change your SATC control head over.
I couldn’t find much online for decent photos (garage is still in a deep-freeze), but these will work (swiped from internet).
This is an ATC (full-automatic, not semi-automatic that our cars have) used on mid ‘70’s full size Chryslers – but it is almost the same as the SATC heads M & J’s use (this version has no blower speed control). The temperature control lever (I outlined in white to make it more visible) is different. To change levers, you need to push down on and then sideways to release the clip (blue arrow), and the lever comes off. The electrical position sensor (yellow arrow) can either be removed or left in place if you so desire.
This is what a conventional temperature lever looks like. There is a tang for a cable loop to go around. The cables used in the late ‘70’s and ‘80’s have quick-disconnect clips on them that look like this:
All the ones I’ve seen are red. The control head base has a quick disconnect socket for cable already made on. Note: those red cable clips have been sturdy, but I’ve noticed as they get older, they can break – so just push enough to disconnect the clip. That said, if cable clip(s) do break, keeping the cables in place with a zip-tie is an easy fix.
I have heard (but not yet verified) that temperature control cables from early ‘80’s pickups and full-size vans will work – but will be a tad long. It is much better for a cable to be “too long” than “too short”.
The rod coming out of evaporator case – which the servo motor turns will work with a cable. The rod (is actually called the blend air door or temperature control door) is threaded and cut so it has a “D” shape to it. It uses a standard SAE nut to hold the lever in place (not sure of size, right off). The lever can be made – but the lever is the same one Chrysler has used on most all vehicles in ‘70’s and ‘80’s. I have one that I installed into my ’86 Fifth Ave to convert it to conventional A/C already, and there is a small chance I took pictures of what it looked like (if pictures didn’t get eaten by a recently died hard drive).
The lever is about 3 inch by 1 inch (75 x 25 mm) with a stud on one end for cable adjuster clip to slide onto (maybe ¼” diameter (6.3 mm) possibly – going by memory).
A person can take a normal sleeved cable and modify it to fit, just as easy (in place of an official cable). Having one of these adjustable clips should make one end easier (see picture, above, with yellow clip). That adjustable clip can be obtained separately.
After the cable changeover, the remaining SATC wiring harness (which is separate from other dash harnesses), the aspirator and evaporator temp sensors can be removed or left in place if one desired.
BudW