charging pressures for ac system

[musky48]

I was wondering what the pressures for an ac unit on a car with 134A should be? Also do you have to look at the high side also or just the low side? Do you take the reading with the car at idle or do you take it at higher RPM?

Thanks
musky

[UncleBob]

with the car running, depends on the type of system and the ambient temps. But low side should be between 10-50psi (cycling) high side can be anywhere from 100-450psi, although pressures over 300psi are less common (when everything is working correctly)

you want to see the system cycle, and sometimes that requires bringing the RPM's up off idle. If its a variable displacement compressor, then it won't cycle.

[musky48]

Thanks for the info, it is much appreciated.

musky