Help with vintage air system
 

Trying to get ac working in my car. Had a shop fill the system and the relay wasn’t working so I got my car back and replaced the relay. System has gas in it but compressor isn’t coming on. When I put gauges on, the low side reads 90 and high side is 100 when the car is just idling. Also, air temp was 86 degrees. Can someone please help me figure out what’s wrong?
Thanks
Jon

I’m going to guess it is not correctly charged. I would evacuate the system and start over again making sure the amount specified by VA is used.

I don’t know about pro shops but I can’t get the specified amount into the system if the compressor is not running.

Don

Thanks for the response. Yeah the compressor wasn’t working so I will have them evacuate the system and try again

Make sure you supply them the exact quantity of R134a to use. Vintage Air systems do not run at the same pressures as most auto AC systems. 1.8 pounds.

Don

Your high and low side pressures equalize with the system off. The pressures, when off, will be roughly ambient outside temp, 90 degrees = roughly 90-100 psi.

How much of that is air/moisture or freon depends on how well the system was evacuated and charged.

You need to jump the clutch and let it run for a few minutes to see what your pressures are doing. That will tell you if it's a mechanical/plumbing/charge issue or electrical issue.

Just went through something similar. Vintage air unit with a binary switch. Was running the cut on through the computer and with a two relay unit going to the electric fans the compressor wouldn't cut on. Now that I switched over to a three relay system, the compressor cuts on and runs like it should. Who knew...