Hi everyone, pulling my hair out over my car. Air conditioning stopped blowing cold, and I've checked about damn near everything:

- Compressor clutch was engaging, but I replaced compressor, dryer, and expansion valve.
- All lines blow through cleanly with no restrictions
- Condenser blows through cleanly with no restrictions
- Evaporator blows through cleanly with no restrictions.

When compressor kicks on, low side drops to nearly zero, while high doesn't budge.

I did not remove the evaporator (really want to avoid that...) but if I send compressed air through the port behind the firewall with the expansion valve removed it comes out the other side fine.

The only thing I'm left with is the the possibility that the new (rockauto) expansion valve is bad but I find that incredibly unlikely.

Thots?

Thanks for your time in advance.

 

You should read ~40psi on the low side. Me thinks you're undercharged.

 

Sounds like expansion valve not working. Can you test with old one?

 

When the AC is off, the low side has pressure. It quickly drops to near zero as soon as you turn on the AC

 

How much refrigerant did you charge the system with? It sounds low.

 

With the system off, pressure should be equal on the high and low side.

 

When evacuating the system can it hold near -30psi of vacuum? Could be a leak if not but to me it also sounds like it's not properly charged. Like SlowCrash said it's supposed to have equal pressure when not engaged.