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I am fixing up my son’s ‘76. One of the things we are trying to figure out is why the ac won’t work. Here are my questions:
1. I believe that the compressor clutch won’t engage unless the proper freon pressure is present in the system- is this correct?
2. If the system is dry, where are the typical places on these C3’s that develop freon leaks?
3. when I look up new compressors, it shows a longer cylindrical one for ‘76. My son’s compressor on his 76 looks like the shorter one, like I have on my 79. I’ll attach a pic of his to this email.
4. there is a second green wiring connector coming off of the back of the compressor. Any idea what that goes to?
5. We currently have the front of the car apart. Is there any way to test the condenser for leaks? If we are going to have to change it, I’d rather do it now while it’s easy to get to.
I am fixing up my son’s ‘76. One of the things we are trying to figure out is why the ac won’t work. Here are my questions:
1. I believe that the compressor clutch won’t engage unless the proper freon pressure is present in the system- is this correct? Yes
2. If the system is dry, where are the typical places on these C3’s that develop freon leaks? Generally if you shell a compressor. A loose hose also
3. when I look up new compressors, it shows a longer cylindrical one for ‘76. My son’s compressor on his 76 looks like the shorter one, like I have on my 79. I’ll attach a pic of his to this email. It maybe that late 76 changed to the R4 compressor, in any case get the one that he currently has.
4. there is a second green wiring connector coming off of the back of the compressor. Any idea what that goes to? Most likely it goes to the binary switch, low pressure cutoff
5. We currently have the front of the car apart. Is there any way to test the condenser for leaks? If we are going to have to change it, I’d rather do it now while it’s easy to get to. Vacuum pump is your friend here
Number 4. wire to idle up solenoid on carburetor if Automatic transmission. And yes Vacuum pump is your friend here. 76 is a VIR system. consider a VIR eliminator kit.
If i am checking leaks i would use dry compressed air and look for holding pressure AND visualy see any leaks..
also if changing to 134 a few other things..including orifice (should inpect that as well for metal).. and of course vacuum after…
My old AC leaked first when the seal at the front of the compressor went bad. The oil sprayed out onto the inside of the hood. If there is dye in the system use a UV flashlight. If someone else has been thru the system it most likely be leaking from a hose connection. I use a little Nitrogen tank hooked up to the gauge hoses and a little leak finder sprayed onto the connections.
Thanks for all of the input. My son is sixteen, and he insists that he pay for the majority of the repairs/upgrades on this car himself. I do admire that about him. Because of that, I think we will leave the ac alone for now. My thinking is that we can convert to an after market system with modern off the shelf freon in a few months. We did the same thing to his 1969 C10 last year, and that aftermarket ac kit functions great. Now my question is- is it possible to remove the old condenser and install the new one later, with the front clip on…or is the only way to do so with the front of the car off. The front is completely off of my son’s ‘76 currently. However, I raised the hood on my ‘79 and it looks like if we took the hood off, it’s possible to change the condenser and/or radiator with the front clip still in tact. Does anyone have any advice on this? I’m thinking we might leave the old condenser out for now, and install the new one that comes with the aftermarket kit in a few months.
parallel flow condenser. 100 ebay. you need to either get the vir eliminator or replace ac evaporator and liquid line and main big hose pair and reciever-dryer. the hose connections at the firewall end are different than your 76 VIR style. need adjustable cycling switch. has to be r12 switch. r134 is bigger thread. sanden compressor. 508 or 709. https://www.ebay.com/itm/30303415723...gAAOSwqRlcQkoA you can find them with the hoses sticking straight up for cheaper and 25 bucks get a GM pad mount cylinder head. (back cover). DO NOT buy one with a serpentine pulley. the new clutch with V belt pulleys is as much as a compressor. this compressor will fit the A6 front mount with a little bit of hole enlargement. and some fabbing to support the rear. adapter mounts for a6 style are expensive. the mount to adapt to R4 mount is about 50 bucks and best way to go. this will get you started in collecting the parts to convert to new r134 system without paying somebody 1500 bucks.
Air Conditioning Overhaul
