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 MANUALSMERCURY2009MARINER BASE, 2.5 7, AWDREPAIR AND DIAGNOSISHEATING, VENTILATION & A/C (HVAC)HVAC CONTROL SYSTEMSHVAC CLIMATE CONTROL SYSTEMDESCRIPTION AND OPERATIONCONTROL COMPONENTSELECTRONIC AUTOMATIC TEMPERATURE CONTROL (EATC)NOTES
2009 Mercury Mariner Base, 2.5 7, AWD
Electronic Automatic Temperature Control (EATC): Notes
2009 Mercury Mariner Base, 2.5 7, AWDSECTION Notes
The HVAC module analyzes input from the following major sources:
- Temperature, airflow mode, blower, A/C and RECIRC selection (made by the vehicle occupants)
- ECON button (hybrid only)
- In-vehicle temperature sensor (non-hybrid only)
- In-vehicle temperature and humidity sensor (hybrid only)
- Ambient temperature sensor
- Sunload sensor (solar radiation sensor)
- Evaporator discharge air temperature sensor
- Vehicle speed
- Engine Coolant Temperature (ECT)
Using these inputs, the HVAC module determines the correct conditions for the following outputs:
- A/C compressor ON/OFF request
- Blower motor speed
- Temperature blend door position
- Airflow mode door position
- Air inlet door position
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.