DTC P1543 - A/C System Performance: Notes

PCM monitors A/C refrigerant pressure and A/C evaporator temperature to determine if A/C system has adequate refrigerant charge. PCM will disable the A/C clutch whenever refrigerant charge drops to less than a predetermined value, to reduce the chance of compressor damage. PCM will cycle the compressor more frequently if the charge is slightly low. PCM determines the A/C charge based on refrigerant pressure and evaporator temperature. PCM uses these 2 inputs to calculate A/C refrigerant charge.