P1436 Cadillac A/C Evaporator Air Temperature Circuit Low

Possible causes

ACET circuit short to ground or SIG RTN.

Damaged ACET sensor.

Damaged PCM.

Tech description

The PCM sources a low current 5 volts on the ACET circuit (this voltage can be measured with the sensor disconnected). As the A/C evaporator air temperature changes, the ACET circuit resistance to SIG RTN (ground) changes (which changes the voltage the PCM detects). When the ACET signal is detected below the self-test minimum, check for shorts to the SIG RTN or ground, which would pull the voltage low.

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)

P1436 Cadillac Description

Indicates the ACET signal input was less than the self-test minimum. The self-test minimum is 0.13 volts.