Well, I am not an AC expert so I am asking for some pointers in troubleshooting my AC system. 1. My AC stopped working some time ago, although it was working when I got the car many years ago. 2. I tried charging it up but it did not work. In the process, I overcharged the system. When I evacuated the system to remove the engine, more than 3 lbs of R12 came out (and the shop conveniently kept it for themselves) 3. As part of the engine out service, I changed to a new Drier, and a new valve which was clearly rusted shut. On the installation of the engine, I tried charging up the system with the old compressor and it did not take any charge. So, I just ignored AC for a while. 4. A few months ago, a. I pulled a vacuum, tried charging it and it took just 1/2 lb. b. Hooked up a gauge set c. Jumped the compressor with 12V and it clicked d. Charged it up again and it did not take any charge. The pressure at the low side and the high side were the same at 50 psi even though the compressor was turning with the clutch engaged. That indicated to me the compressor was bad. e. Today, I removed the compressor and tested manually on the bench. The clutch engaged OK with 12V across it. By turning the pulley, I can feel pressure building up inside the compressor if I cover the holes up. So, it seems the compressor is OK, or is my test not good enough? If compressor is OK, what is the next step in troubleshooting an AC system? Is there blockage? How to look for it?
Sounds like it is plugged somewhere. With a good vacuum drawn it has enough internal capacity to take the entire charge without help from the compressor. I'd start disconnecting hoses and blow air through it. Just remember the expansion valve will let a little air to blow through. Disconnect both sides and the compressor and blow through everything. I have also seen shops add oil at every service until it has so much oil there is no room for freon but you would still get pressure. If you need a compressor. https://www.discountacparts.com/buynow/1983/Ferrari/308/A-C_Compressor/60-01013_A1?src=pla&pt_source=googleads&pt_medium=cpc&pt_campaign=DACP PLA Shopping&pt_adgroup=[60-0] PLA A/C Compressor&gclid=CjwKCAiA_P3jBRAqEiwAZyWWaGw
So I disconnected all the lines, tested them with compressed air and no clogs are found anywhere. No clogs through the condenser either. Finally connected all back and blew air from high side and felt some air coming out the low side hose (minus the compressor now sitting on the bench). It seems system is not clogged. Are we now looking at the compressor again?
Mate, the compressor should pump to 250psi - using your hand to feel the pressure is useless. It might pump enough to break the seal of your hand, but that's not a good test. Personally, I'd get a new one.
With the compressor off the suction and discharge pressure will be the same. With the compressor running the suction pressure should drop and the discharge should increase but this is not happening ? With the compressor on the bench can you find a way to connect up a gauge to the suction side and see if the suction pressure drops from atmospheric to a negative pressure when you turn the pulley- just to show it will suck. How are you charging up the system from empty ? And how much gas should the system hold ?
FYI, here are high and low side pressures vs ambient temperature for 134a and R12. Image Unavailable, Please Login Image Unavailable, Please Login
With the compressor running, by connecting 12V directly across the two wires, the pressure on the low side is 50 psi from the r12 tank and the high side pressure is 50 psi. No difference With the compressor on the bench, I can also connect 12 v across the wires and turn the compressor by hand and feel the suction side "sucking." But I am willing to entertain that bench testing is no good. I tried charging by hooking up a vacuum on the low side (and then the high side) running a vacuum, and connecting the r12 tank to that side via a pressure AC gauge set. I also tried charging by running the car, applying 12V across the wires (hearing the clutch click) and then connecting the tank to the low pressure side. In both cases, it only took about 1/2 lb of R12 where it should take 1kg (2.2 lbs).
When you were trying to charge it, did the condenser fan cut in ? Also with the charging hoses connected, what suction pressure do you get when you shut the outlet valve on the f12 tank. ie will the compressor pull a vacuum up to the closed off tank What is odd here is that the suction is not going down and the discharge is not going up. If the system was blocked then the discharge presure should go up, regardless of anything else. Other thing to check is the compressor pulley, the clutch is operating but is the pulley slipping so the compressor is not up to speed which would explain a lot
What is the ambient temperature and what equipment are you charging with? It is hard to get a charge in with lower ambient temperature unless you have a heated tank or charge with liquid (tank valve down).
I live in California where it is 60-70 all day. I just charged up a 348 with R12 using the same set up. Did not even pull a vacuum, just hooked up the tank to the low side with a gauge set. It went right in, full charge. It's not the set up. It's the car.
