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 MANUALSMERCURY2011MARINER PREMIER, 2.5 7, AWDREPAIR AND DIAGNOSIS (SINGLE PAGE)QUICK LOOKUPSDTC INDEXCLIMATE CONTROL SYSTEM DTCSEXCEPT HYBRIDHVAC MODULE
2011 Mercury Mariner Premier, 2.5 7, AWD
HVAC Module
2011 Mercury Mariner Premier, 2.5 7, AWDSECTION HVAC Module
HVAC MODULE DIAGNOSTIC TROUBLE CODE (DTC) LIST - EXCEPT HYBRID
| DTC | Description | Action to Take |
|---|---|---|
| B1200 | Stuck Button | Button held too long may set DTC. ATTEMPT to clean buttons. If code returns, INSTALL a new HVAC module. REFER to CLIMATE CONTROL article. |
| B1251 | Air Temperature Internal Sensor Circuit Open | GO to PINPOINT TEST C . |
| B1253 | Air Temperature Internal Sensor Circuit Short To Ground | GO to PINPOINT TEST C . |
| B1255 | Air Temperature External Sensor Circuit Open | GO to PINPOINT TEST D . |
| B1257 | Air Temperature External Sensor Circuit Short To Ground | GO to PINPOINT TEST D . |
| B129B | Driver Blend Door Actuator, Drive Circuit(s) Shorted to Battery Voltage | GO to PINPOINT TEST N . |
| B129C | Driver Blend Door Actuator, Feedback Circuit Open or Shorted to Battery Voltage | GO to PINPOINT TEST N . |
| B129D | Driver Blend Door Actuator, Feedback Circuit Shorted to Ground | GO to PINPOINT TEST N . |
| B129F | Passenger Blend Door Actuator, Drive Circuit(s) Shorted to Battery Voltage | GO to PINPOINT TEST N . |
| B12A0 | Passenger Blend Door Actuator, Feedback Circuit Open or Shorted to Battery Voltage | GO to PINPOINT TEST N . |
| B12A1 | Passenger Blend Door Actuator, Feedback Circuit Shorted to Ground | GO to PINPOINT TEST N . |
| B12A2 | Passenger Blend Door Actuator, Slow or Door Obstructed | GO to PINPOINT TEST N . |
| B12A4 | Mode Door Actuator, Drive Circuit(s) Shorted to Battery Voltage | GO to PINPOINT TEST I . |
| B12A5 | Mode Door Actuator, Feedback Circuit Open or Shorted to Battery Voltage | GO to PINPOINT TEST I . |
| B12A6 | Mode Door Actuator, Feedback Circuit Shorted to Ground | GO to PINPOINT TEST I . |
| B12A7 | Mode Door Actuator, Slow or Door Obstructed | GO to PINPOINT TEST I . |
| B12A9 | Recirc Door Actuator, Drive Circuit(s) Shorted to Battery Voltage | GO to PINPOINT TEST H . |
| B12AF | Front Blower Motor Relay Drive Circuit Shorted to Battery Voltage | For EMTC
systems, GO to PINPOINT TEST O
. For DATC systems, GO to PINPOINT TEST Q . |
| B12B0 | Front Blower Motor Relay Drive Circuit Open or Shorted to Ground | For EMTC
systems, if the blower motor is inoperative, GO to PINPOINT TEST O
. For EMTC systems, if the blower motor is always on, REPAIR circuit CH123 (VT/GN) for a short to ground. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. For DATC systems, if the blower motor is inoperative, GO to PINPOINT TEST Q . For DATC systems, if the blower motor relay is always on, REPAIR circuit CH123 (VT/GN) for a short to ground. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. |
| B12B1 | Front Blower Motor PWM Drive Circuit Shorted to Battery Voltage | GO to PINPOINT TEST R . |
| B12B2 | Front Blower Motor PWM Drive Circuit Open or Shorted to Ground | GO to PINPOINT TEST Q . |
| B12B3 | Blend Door Actuator, Drive Circuit(S) Shorted to Battery Voltage | GO to PINPOINT TEST N . |
| B12B5 | Blend Door Actuator, Feedback Circuit Open or Shorted to Battery Voltage | GO to PINPOINT TEST N . |
| B12B6 | Blend Door Actuator, Feedback Circuit Shorted to Ground | GO to PINPOINT TEST N . |
| B12B7 | Blend Door Actuator, Slow or Door Obstructed | GO to PINPOINT TEST N . |
| B12B8 | Driver Blend Door Actuator, Slow or Door Obstructed | GO to PINPOINT TEST N . |
| B12B9 | Vref (5V) Drive Circuit Shorted to Battery Voltage | REPAIR circuit LH111 (BN/WH) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. |
| B12BA | Vref (5V) Drive Circuit Shorted to Ground | REPAIR circuit LH111 (BN/WH) for a short to ground. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. |
| B1342 | Module is Faulted | INSTALL a new HVAC module. REFER to CLIMATE CONTROL article. |
| B1676 | Battery Voltage Out of Range | GO to PINPOINT TEST S . |
| B2426 | Passenger Solar Radiation Sensor Circuit Open | GO to PINPOINT TEST E . |
| B2427 | Passenger Solar Radiation Sensor Circuit Short to Ground | GO to PINPOINT TEST E . |
| B2477 | Module Configuration Failure | INSTALL a new HVAC module. REFER to CLIMATE CONTROL article. |
| B2795 | Driver Solar Radiation Sensor Circuit Short to Ground | GO to PINPOINT TEST E . |
| B2796 | Driver Solar Radiation Sensor Circuit Open | GO to PINPOINT TEST E . |
| B2826 | Front Evaporator Temp Sensor Circuit Failure | GO to PINPOINT TEST F . |
| B2827 | Front Evaporator Temp Sensor Short to Ground | GO to PINPOINT TEST F . |
| B297A | Blend Door Actuator, Drive Circuit(s) Open | GO to PINPOINT TEST N . |
| B297B | Blend Door Actuator, Drive Circuit(s) Shorted to Ground | GO to PINPOINT TEST N . |
| B297C | Driver Blend Door Actuator, Drive Circuit(s) Open | GO to PINPOINT TEST N . |
| B297D | Driver Blend Door Actuator, Drive Circuit(s) Shorted to Ground | GO to PINPOINT TEST N . |
| B297E | Passenger Blend Door Actuator, Drive Circuit(s) Open | GO to PINPOINT TEST N . |
| B297F | Passenger Blend Door Actuator, Drive Circuit(s) Shorted to Ground | GO to PINPOINT TEST N . |
| B298A | Mode Door Actuator, Drive Circuit(s) Open | GO to PINPOINT TEST I . |
| B298B | Mode Door Actuator, Drive Circuit(s) Shorted to Ground | GO to PINPOINT TEST I . |
| B298C | Recirc Door Actuator, Drive Circuit(s) Open | GO to PINPOINT TEST H . |
| B298D | Recirc Door Actuator, Drive Circuit(s) Shorted to Ground | GO to PINPOINT TEST H . |
| U0140 | Lost Communication With Body Control Module (GEM) | CLEAR The DTCs. REPEAT the self-test. If the DTC returns, REFER to MODULE COMMUNICATIONS NETWORK article to diagnose the lost communication with the GEM. |
| U0300 | Internal Control Module Software Incompatibility | INSTALL a new HVAC module. REFER to CLIMATE CONTROL article. |
| U2050 | No Application Present | INSTALL a new HVAC module. REFER to CLIMATE CONTROL article. |
| U2051 | One or More Calibration Files Missing / Corrupt | INSTALL a new HVAC module. REFER to CLIMATE CONTROL article. |
| All Other DTCs | - | REFER to the Master DTC Chart in MULTIFUNCTION ELECTRONIC MODULE article. |
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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.