B1348

CIRCUIT DESCRIPTION
The HVAC control processor monitors the signal circuit of the A/C low pressure switch. If no voltage is detected on the signal circuit the HVAC control processor interprets that as low refrigerant pressure and disables the A/C compressor clutch. If voltage is detected on the signal circuit the refrigerant pressure is considered to be normal. Usually, the A/C low pressure switch is closed above 69 kPa (10 psi).

CONDITIONS FOR RUNNING THE DTC
The ignition is turned ON and the engine is running.

CONDITIONS FOR SETTING THE DTC
^ The HVAC control processor detects that the A/C system has been requested.
^ The HVAC control processor does not detect voltage on the signal circuit of the A/C low pressure switch.

ACTION TAKEN WHEN THE DTC SETS
^ The HVAC control processor will not illuminate the Malfunction Indicator Lamp (MIL).
^ The message LOW REFRIGERANT-A/C OFF is displayed on the driver information center (DIC).
^ The A/C compressor clutch is disabled.

CONDITIONS FOR CLEARING THE DTC
^ The DTC will become history if the HVAC control processor no longer detects a condition.
^ The history DTC clears after 50 fault-free ignition cycles.
^ The DTC can be cleared with a scan tool.

DIAGNOSTIC AIDS
If the condition is not present, refer to Testing for Intermittent and Poor Connections in Diagnostic Aids.

TEST DESCRIPTION

Steps 1-2:

Steps 3-14:

The numbers below refer to the step numbers on the diagnostic table.
2. Verify the ambient air temperature and the refrigerant level before continuing with the diagnosis of the DTC.
3. Verifies that battery voltage is supplied to the A/C low pressure switch.
4. Verifies the condition of the fuse that supplies voltage to the A/C low pressure switch is good.
5. Inspects the ignition 1 voltage circuit for a short to ground.
6. Verifies the condition of the A/C low pressure switch.
7. Inspects the signal circuit of the A/C low pressure switch for a high resistance or for an open.
10. Inspects the ignition 1 voltage circuit for an open.
11. Inspects the signal circuit of the A/C low pressure switch for a short to ground.
13. Perform the recalibration procedure for the HVAC control processor.