A048

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

In the process of controlling the compressor clutch, the Air Conditioning Programmer (ACP) monitors certain system inputs for an indication of low refrigerant charge. The ACP monitors the normally closed low refrigerant pressure switch at pin "C3." The status of the low pressure switch is checked prior to compressor engagement. If the return voltage to the ACP indicates the switch is open, the ACP sets DTC A048 and does not command the compressor clutch to engage. The compressor clutch remains disengaged until DTC A048 is cleared. Additionally, the ACP goes into ECON mode and the 'ECON' indicator is displayed on the Electronic Climate Control (ECC). The Driver Information Center (DIC) displays message "VERY LOW REFRIGERANT - A/C COMPRESSOR OFF" to warn the operator.

FAILURE CONDITIONS

A048 - VERY LOW REFRIGERANT PRESSURE CONDITION sets if the low refrigerant pressure switch remains open for several minutes.

ACTION TAKEN

1. DIC displays message "VERY LOW REFRIGERANT - A/C COMPRESSOR OFF" to warn operator.

2. ACP will not command A/C Compressor clutch engagement until DTC is cleared.

NOTES ON FAULT TREE

1. Check current state of low pressure switch.

2. Check circuits to low pressure switch.

3. Check HVAC refrigerant system pressure.

4. Check for a restriction in HVAC refrigerant system.

5. Check for intermittent short or open.

NOTES ON INTERMITTENT CONNECTION
If an intermittent DTC is being set, select ACP Snapshot Data for DTC and note value of ACP data parameter. Manipulate the related wiring while observing ACP data parameter. If a failure is induced, the displayed data parameter value will be outside the sensors normal operating range.