System Performance Test

R-134a systems require the use of special service equipment designed specifically for R-134a systems. R-12 servicing equipment cannot be used on R-134a systems.


1. Connect manifold gauge set to system.
2. Start and run engine at 2000 RPM, then turn A/C system On.
3. Set temperature control to cool and blower motor to high.
4. If compressor clutch does not engage, jumper battery power to green/black wire at clutch connector.
5. Wait until air conditioning system stabilizes, then check readings at high and low pressure gauges.
6. Normal reading for high pressure gauge should be 199-220 psi. Normal reading for low pressure gauge should be 19-21 psi. for 1989-90 models or 28-43 psi. for 1991 models.
7. If pressure is not within specifications, record stabilized pressure and perform necessary system diagnosis.