AC Won't Charge
 

I have a 1990 that is giving us fits. When I bought the car the AC didn't work. There was no freon in the system so we pulled a vacuum and tried to get it to take r134. The car had r134 fittings. It would take only about half a can of freon even with the low pressure sensor shorted. The compressor was engaged and turning. I then decided to replace the compressor with a new Denso compressor. I did this and replaced the acumulator, hoses, evaporator, expansion orifice and filter. The only thing not replaced was the condenser. We then pulled a vacuum and again it would only take about half a can of r134.

Next I took the car to a reputable AC repair shop. They flushed the system and replaced the schrader valves. They had the car for a week and couldn't get it to take the freon. I brought the car home.

Today I disassembled the system and blew out all the parts but the compressor. I replaced the oil with 8 ounces of new oil and all new o-rings. I pulled a vacuum and checked for leaks. I then tried to add the freon, it took a little more than half a can and that's all it would take. The low pressure side gauge never read below 95psi.




Any ideas?

Re: AC Won't Charge
 

I had a problem years back with the A/C not working. If I remember correct the A/C dash control will set a code and has to be cleared to allow the system to work. Check the FSM for help. Hope this helps.

Re: AC Won't Charge
 

It throws a low freon code 9, but I'm bypassing the low pressure sensor to get the compressor to run.

Re: AC Won't Charge
 

I think I found the problem. The low pressure schrader valve is not releasing allowing freon to enter the low pressure side. The "new" r234 adapter is not depressing the second schrader valve.

Re: AC Won't Charge
 

I had exactly that same issue when I converted my to R234a.
The problem ended up being the old R12 original schrader valve pin being bent just slightly. I replaced it and continued on.