In the process of controlling the compressor clutch, the heater and A/C programmer monitors certain inputs for an indication of a low refrigerant charge. If the refrigerant state of charge falls below approximately 1/4 capacity, the heater and A/C programmer is capable of detecting this condition. The programmer displays VERY LOW REFRIGERANT--A/C COMPRESSOR OFF on the driver information center (DIC) in order to warn the operator.

The heater and A/C programmer determines the state of the charge by monitoring the temperature change in the low temperature sensor during the compressor engagement. This temperature drop is referenced by the heater and A/C programmer as a function of the ambient air temperature. If the refrigerant charge is too low, the refrigerant boils instantaneously after passing through the orifice tube. This action creates a large rapid change in the low temperature sensor reading. After several incidents are counted, the heater and A/C programmer sets DTC B1347. The message VERY LOW REFRIGERANT--A/C COMPRESSOR OFF will be displayed on the DIC. If a DTC B1347 is set, the compressor clutch disengages and remains disengaged until DTC B1347 is cleared. DTC B1347 may repeat if excessive pressure exists in the A/C charging station tank. Repair the A/C charging station before properly diagnosing DTC B1347.

The low side refrigerant temperature drops too quickly during several of the compressor cycles.

1. Perform the Diagnostic System Check before continuing with the diagnosis of this DTC.

2. This test inspects for an intermittent open or a short in the pressure switch circuit.

3. This test inspects for restrictions in the refrigerant system.