A/C Signal: Description and Operation

AIR CONDITIONING (A/C) CONTROLS INPUT

NOTE: The A/C control system information applies to factory installed air conditioning units only.

A/C SELECT SIGNAL
When the A/C switch is in the ON position and the A/C low-pressure switch is closed, an input signal is sent to the Jeep/Truck Engine Controller (JTEC). The signal informs the JTEC that the A/C has been selected. The JTEC adjusts idle speed to a pre-programmed rpm through the idle air control (IAC) motor to compensate for increased engine load.

A/C REQUEST SIGNAL
Once A/C has been selected, the JTEC receives the A/C request signal from the evaporator switch. The input indicates that the evaporator temperature is in the proper range for A/C application. The JTEC uses this input to cycle the A/C compressor clutch (through the A/C relay) It will also determine the correct engine idle speed through the IAC motor position.

If the A/C low-pressure switch opens (indicating a low refrigerant level), the JTEC will not receive an A/C select signal. The JTEC will then remove the ground from the A/C relay. This will deactivate the A/C compressor clutch.

If the evaporator switch opens, (indicating that evaporator is not in proper temperature range), the JTEC will not receive the A/C request signal. The JTEC will then remove the ground from the A/C relay, deactivating the A/C compressor clutch.