A/C system low or over charge with refrigerant
Faulty A/C refrigerant pressure sensor
Cooling fans in-operative
A/C refrigerant pressure sensor circuit open or shorted
A/C refrigerant pressure sensor circuit poor electrical connection
Engine Light ON (or Service Engine Soon Warning Light)
A/C Blows Warm
The powertrain control module (ECM) monitors the high side refrigerant pressure via a A/C refrigerant pressure sensor. When the pressure is high the signal voltage is high. When the pressure is low the signal voltage is low. When pressure is high the ECM commands the cooling fans on. When pressure is too high or too low the PCM will not allow the A/C compressor clutch to engage.