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Home >> Ford >> 2000 >> Contour SE, 2.5 L, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 1975 (Engine Controls - Powertrain DTC Charts And Descriptions - (Hybrid)) >> DTC Diagnosis >> P0538 - A/C Evaporator Temperature (ACET) Circuit High

P0538 - A/C Evaporator Temperature (ACET) Circuit High

WARNING: This page is about a different car, the 2007 Mercury Mariner and 2007 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
P0538 - A/C EVAPORATOR TEMPERATURE (ACET) CIRCUIT HIGH

Description:  Indicates the ACET signal input is greater than the self-test maximum. The self-test maximum is 4.5 volts.
Possible Causes: 
  • ACET circuit open
  • SIG RTN circuit open to the ACET sensor
  • ACET circuit short to voltage (VREF)
  • Damaged ACET sensor
Diagnostic Aids:  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 circuits (ACET or SIG RTN), which cause the voltage to remain high. Although not as probable, also check for a short to voltage (VREF).
Application  Key On Engine Off  Key On Engine Running  Continuous Memory 
All   refer to PINPOINT TEST DJ .
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