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.
HVAC Module Self-Test
2010 Mercury Mariner Hybrid, AWDSECTION HVAC Module Self-Test
WARNING: This page is about a different car, the 2010 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.
- The HVAC module self-test will not detect concerns associated with data link messages like engine coolant temperature or vehicle speed signals. A scan tool must be used to retrieve these concerns.
- The HVAC module self-test will detect concerns in the system control functions and will display hard DTCs. Hard DTCs identify faults which are present during the self-test. The vehicle interior/ambient temperature should be between 4-32°C (40-90°F) when carrying out the self-test. If the temperatures are not within the specified ranges, false temperature sensor DTCs will be displayed.
- The self-test can be initiated at any time. Normal operation of the system stops when the self-test is activated.
- To enter the self-test, press the OFF and FLOOR buttons simultaneously and then press the AUTO button within 2 seconds. The display will show the fan speed indicator illuminating from low to high. The test may run as long as 30 seconds. Record all DTCs displayed.
- If any DTCs appear during the self-test, follow the diagnostics procedure given under ACTION for each DTC given.
- If a condition exists but no DTCs appear during the self-test, go to Symptom Chart - Climate Control Systems .
- To exit the self-test and clear all DTCs, press the front DEFROST button. The HVAC control assembly will then turn OFF (display blank) and all DTCs will be cleared.
- Always exit the self-test before powering the system down (system turned OFF).
- If a condition exists, but no on-demand DTCs appear during the self-test, carry out the HVAC Module - Retrieve Continuous DTCs self test.
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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.