Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSLINCOLN2006ZEPHYRREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROLS - POWERTRAIN DTC CHARTS & DESCRIPTIONS (EXCEPT DIESEL & HYBRID)DTC DIAGNOSISDTC P0538: A/C EVAPORATOR TEMPERATURE (ACET) CIRCUIT HIGH INPUT
2006 Lincoln Zephyr
DTC P0538: A/C Evaporator Temperature (ACET) Circuit High Input
2006 Lincoln ZephyrSECTION DTC P0538: A/C Evaporator Temperature (ACET) Circuit High Input
P0538 - A/C EVAPORATOR TEMPERATURE (ACET) CIRCUIT HIGH INPUT
| Description: | Indicates the ACET signal input was greater than the self-test maximum. The self-test maximum is 4.5 volts. | ||
| Possible Causes: |
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| Diagnostic Aids: | The powertrain control module (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 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 | GO to Pinpoint Test DJ . | ||
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.