P1436 Buick A/C Evaporator Air Temperature Circuit Low

P1437 Buick A/C Evaporator Air Temperature Circuit High

Possible causes
  • ACET circuit open.
  • SIG RTN circuit open to the ACET sensor.
  • ACET circuit short to power (VREF).
  • 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 above the self-test maximum, check for open cirucits (ACET or SIG RTN), which would cause the voltage to remain high. Although not as probable, also check for a short to power (VREF).
    Symptoms
    – Engine Light ON (or Service Engine Soon Warning Light)
    P1437 Buick Description

    Indicates the ACET signal input was greater than the self-test maximum. The self-test maximum is 4.5 volts.

    Buick Vehicle:Buick Regal – ?Buick Riviera – ?Buick LaCrosse – ?David Dunbar Buick – Buick Century – Buick LaCrosse – Buick LeSabre – Buick Lucerne – Buick Park Avenue – Buick Regal – Buick Verano – Buick Enclave – Buick Encore – Buick Rainier – Buick Rendezvous – Buick Terraza – Buick Riviera