A047

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

In the process of controlling the compressor clutch, the ACP monitors certain inputs for an indication of low refrigerant charge. If the system refrigerant state of charge should fall below approximately one third its capacity, the ACP is capable of detecting this condition and will display a driver warning message to warn the operator.

The ACP determines the state of charge by monitoring the temperature change in the low side temperature sensor during initial moments of each compressor engagement. This temperature drop is referenced in a table in the ACP as a function of outside air temperature. If the refrigerant charge is too low, the refrigerant will boil instantaneously after it passes through the orifice tube, creating a rapid large change in the low side temperature reading. If the temperature change is too great, a Low and/or Very Low Refrigerant counter is incremented in the ACP. Once the counter has reached a calibration value, a LOW (A046) or VERY LOW (A047) refrigerant level is determined and displayed to the owner. If a A047 is detected, the compressor clutch will disengage and remain disengaged until the diagnostic codes are cleared.

FAILURE CONDITION(S)

A046 Low Refrigerant Warning will set if the low side refrigerant temperature drops too quickly during several compressor cycles for vehicles built prior to VIN break-point PU817986 and PU610283.

A047 Very Low Refrigerant Warning will set if the low side refrigerant temperature drops much too quickly during several compressor cycles or the low refrigerant pressure switch opens during several compressor cycles.

ACTION TAKEN

A046 Display Low A/C Refrigerant - 'SERVICE A/C SOON' message on DIC for vehicles built prior to VIN break-point PU817986 and PU610283.

A047 Display 'VERY LOW REFRIGERANT - A/C COMPRESSOR OFF' message on DIC. Disable compressor until diagnostic codes are cleared.

NOTES ON FAULT TREE

1. Check for intermittent open or short in pressure switch circuit.

2. Checks for restriction causing intermittent low pressure condition.

3. Checks for restriction within the refrigerant system.

4. An offset in the ACP temperature sensors AD26 Actual Outside or AD28 Low Side may cause the triggering of a false code. AFTER A LONG COLD SOAK (preferably overnight) IN A SHADED, COOL ENVIRONMENT enter diagnostic WITHOUT STARTING THE ENGINE. All the listed sensor readings should agree with 2°C.

NOTE: Code A046 was disabled for vehicles built after VIN break-point PU817986 and PU610283.