370zSTL

After looking at the service manual (very limited informations).
Im gonna copy and paste the information here, you can find this information @ HA-5

System Description INFOID:0000000004507068
REFRIGERANT CYCLE
Refrigerant Flow
The refrigerant flows from the compressor, through the condenser with liquid tank, through the evaporator, and
back to the compressor. The refrigerant evaporation in the evaporator is controlled by an externally equalized
expansion valve, located inside the evaporator case.
Freeze Protection
To prevent evaporator from freezing up, the evaporator air temperature is monitored, and the voltage signal to
the A/C auto amp. makes the A/C relay go OFF and stop the compressor.
REFRIGERANT SYSTEM PROTECTION
Refrigerant Pressure Sensor
• The refrigerant system is protected against excessively high- or low-pressures by the refrigerant pressure
sensor, located on the liquid tank. The refrigerant pressure sensor detects the pressure inside the refrigerant
line and sends the voltage signal to the ECM if the system pressure rises above, or falls below the specifications.
• ECM turns the A/C relay to OFF and stops the compressor when the high-pressure side detected by refrigerant
pressure sensor is following conditions;
- Approximately 3,120 kPa (31.8 kg/cm2, 452 psi) or more (Engine speed is 1,500 rpm or more.)
- Approximately 2,740 kPa (27.9 kg/cm2, 397 psi) or more (Engine speed is less than 1,500 rpm.)
- Approximately 120 kPa (1.2 kg/cm2, 17 psi) or less

so you can have faulty pressure sensor, low on refrigerant, relay, clogged or crushed high-pressure pipe located between compressor and condenser.

I would hook up a manifold gauge to check the high/low side pressures and go from there. This is first thing I do to customer vehicles with a/c problems. Hook up an a/c machine with manifold gauges built in, I can figure it out right away whats wrong with the customer's vehicle.

Use REFRIGERATION SYSTEM SYMPTOMS under HA-7 and HA-8 to diag with a manifold gauge.

I hope this helps....

If you can get pressure readings and post in here, I can help you with diag.

I need high/low pressure readings @ idle and @ 2-3k rpm