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P1437 - A/C Evaporator Air Temperature Circuit High

WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2007 Mercury Mountaineer, 2007 Mercury Monterey, 2007 Mercury Montego, 2007 Mercury Milan, and 2007 Mercury Mariner. However, it is still accessible from the selected car via links, so may be relevant.
P1437 - A/C EVAPORATOR AIR TEMPERATURE CIRCUIT HIGH

Description:  Indicates the A/CET signal input was greater than the self-test minimum. The self-test maximum is 4.5 volts.
Possible Causes: 
  • A/CET circuit open
  • SIG RTN circuit open to A/CET sensor
  • A/CET circuit short to voltage (VREF)
  • Damaged A/CET sensor
Diagnostic Aids:  The powertrain control module (PCM) sources a low current 5 volt reference on the A/CET circuit (this voltage can be measured with the sensor disconnected). As the A/C evaporator air temperature changes, the A/CET circuit resistance to SIG RTN (ground) changes (which changes the voltage the PCM detects). When the A/CET signal is detected above the self-test maximum, check for open circuits (A/CET or SIG RTN), which would 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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