AC Won't Charge

[365gtb4]

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?

[tpr60]

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.

[365gtb4]

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

[365gtb4]

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.

[scottfab]

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.

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.