Vitaminmopar

I am at the point where I want to restore the A/C evaporator and heater boxes while I have them removed from the car. I wanted to have the evaporator flushed and leak tested as it has been open for a long time. Today I called three local A/C shops and all stated that unless it was in the car no can do, two suggested calling a radiator shop. I did that and no solution there either. So I think DIY is necessary. Now I should inform you I have never serviced A/C before in any car. Having stated that I do have an A/C vacuum pump and some old R12 gauges and a new 30 lb bottle of R12. What fittings do I need to plug the evaporator ports and be able to connect a vacuum pump. I think the evaporator top port is #12 male o-ring and the bottom port is #6 female o-ring and finally the small tube for the STV size I don't know. I'm clueless as to what the fitting size refers too, maybe AN fittings? If I flush the evaporator myself I plan on reverse flow using acetone or denatured alcohol with shop air.

If I can not flush and test the evaporator by itself the other option is to connect everything up out of the car. The problem with that is I don't have serviceable components past the evaporator and I have not settled on what compressor I want to use but leaning towards Pro6ten.

GTOguy

You can buy the actual AC flush fluid at any auto parts store. Don't use anything else. After that, all you need to do is seal up the fittings with either rubber plugs or caps, but one must have a nipple for a vacuum pump. You can even use a hand vacuum pump. Draw absolute vacuum (29.5" HG) and let the set-up sit for a half hour or so. If the system is still holding vacuum at 29.5", you are good to go. You can try to pressurize it using 50PSI max, and immerse it in a tank or tub of water and check for bubbles as well. IME, evaporators rarely fail. Usually, it's the condenser or the compressor. In fact, in 40 years in the business, I personally have never had to change an evaporator.

Milliamp

If you can hook everything up,either inside the car or outside, purchase new lines (high and low pressure) hook up your vac. pump and pull a vacuum. Turn the pump off and watch the gauges to see if it holds a vacuum. You will get a lot of guys who will tell you a lot of good info, but for my 2 cents I would not introduce any more moisture to the system that is there already. If it does not hold a vac. borrow a leak detector put a pound of R12 in the system and go hunting, you will find it if you look long enough. When you said you don't have any other components you do have a condenser, expansion valve, line filter etc.. If all this works and you put everything together i.e.: back in the car let the pump run for 24 hours to rid all the moisture that has been collecting while the system was opened. One more thing remember one drop of liquid refrigerant in the eye and you are going to be using a white cane, wear goggles and be careful if you don't know something ask don't just jump in you can get hurt real bad. Sorry I didn't mean to get wordey wish you lot of luck.
Tom

Powershift

Agree with GTOguy. Evaporators almost never go bad...........but you can clean and test to make yourself feel better. AC cleaners are the best, but mineral spirits and acetone final flush are fine if you must.

Send me a PM and I will send you back a couple of charts from AC DELCO with all the various AC connection sizes. You can buy the connection fittings from LICS and ac-kits at autoacforum.com. https://www.autoacforum.com Then you have to find a way to connect the other end to your air pressure source. Purists will say to only use bottled nitrogen.......and that is true.........but dry shop air will work if you must. 40-50 psig is fine for testing. Immerse it under water in a drum and check for bubbles.

If outside is very dirty, use commercial ac coil cleaner and water rinse.

When you finish all your tests and cleaning, dry it out very well (did I say very well) and then seal it up with rubber stoppers or poly wrapping on the ends connections and store indoors.

Forget the AN fittings.............the GM AC system uses it own fittings and o-rings. You may just have to use a flexible rubber tubing or clear Tygon tubing on the end of the small diameter tubing for testing and use a hose clamp to hold it on and a small bolt for a plug.

Larry

Vitaminmopar

Thanks GTO Guy, tomandjanet, and Powershift! As stated I do not have serviceable components past the evaporator. I became so focused on getting the evap coil tested by a shop I overlooked other possibilities. I think I can plug the cut hoses, get an o-ring kit, connect the expansion valve and STV body to the evaporator and use the Schrader valve ports on the STV for vac/pressure. I will have to fashion a gasket for the lower half of the STV as the guts are gone. Also thanks for the safety tip, I will be sure and wear a face shield when charging. Couple of other questions.

1. I have three used expansion valves with the J bulb, can I clean and test these? There are three replacement expansion valve sensor bulb styles, repo J, coil end, and flat. Can't see how the coil style would work. Is the J style the only one to use?
2. Condenser may/may not be serviceable. I was thinking of replacing it out right with a parallel flow versus the original serpentine style. My thinking is it might marginally improve the refrigeration efficiency of the system using R12 and be ahead if I decide at some point to use R134. Yes/No?

I have a C4 evaporator case. I am considering modifying the C2 evaporator case to increase air flow into the cabin using a C4 model blower motor and cage as the original C2 blower inlet opening is small/tiny. I will have to cut the inlet side opening to accept the larger C4 blower mount section. I think the C4 blower mount can be grafted in using fiberglass and look stock from above. The C4 evaporator coil size looks the same as the C2. I have a spare C2 evaporator case and besides it is a hobby not an investment.

Powershift

1. J-type are best. I have a procedure to test if needed. It is an Autozone procedure from their the library. I feel that if you securely anchor the coil type to the evaporator outlet tubing and then cover with the tar/putty insulation material you would be okay.

2. Yes, get the parallel flow. You can also use Ester oil which is good for both R12 and R134a.............although I still like mineral oil for R12 only.

Larry

Mike Geary

One thing I always try to remember to do when the opportunity is there --- check the screen filter on the expansion valve input.

Powershift

Mike:

The factory expansion valves should all have screens. Replacement expansion valves not so much.

But agree to check what is there, clean if needed, or replace. They are getting hard to find anymore, but I still have a few left.

Larry