Circuit Test/Check - HVAC System

OPERATING CONDITIONS
The PCM will energize the A/C clutch whenever the engine is running and A/C has been requested, unless any of the following conditions are met:

- Wide Open Throttle (WOT).
- A/C head pressure greater than 492 psi or less than 1 psi (as determined by the A/C refrigerant pressure sensor).
- Evaporator temperature sensor less than 1°C (33°F).
- Low ignition voltage.
- Intake air Temperature (IAT) greater than 151°C (3O4°).
- Engine speed greater than 5200 RPM.
- Engine Coolant Temperature (ECT) greater than 124°C (255°).

DIAGNOSIS
Chart C-10 should be used for diagnosing the electrical portion of the A/C circuit. Refer to Computers and Control Systems. Testing and Inspection

The Tech 1 will be used in diagnosing the system, as it has the ability to monitor the A/C request input to the PCM, A/C status, A/C system pressure, as well as displaying when the PCM has commanded the A/C clutch "ON."