F-150 / Mark LT 2011–2012 A/C Control Module Troubleshooting

Important: This guide applies specifically to the separate A/C Control Module. It does not apply to the dash-mounted climate control panel, FCIM, touchscreen, LCD, buttons, or knobs.

If your problem involves a blank or malfunctioning LCD, sticky or unresponsive buttons, damaged knobs, backlighting, or touchscreen operation, this A/C Control Module repair will not correct those issues.

Common reference part numbers for this module include BL3T-18C612-AD and BL3T-18C612-AF. Other compatible part number revisions may exist.

What This Repair Addresses

This repair is intended for internal A/C Control Module failures such as:

• Fan speed control not responding / no control output to the fan or blower system

• Temperature control not responding / no control output to the blend door actuator

If the repaired module has been reinstalled and the original problem is still present, follow the checks below before assuming the module is still faulty.

Step 1: Confirm the Original Symptom

Determine whether the problem still matches the symptoms this repair is intended to correct.

If the LCD, buttons, knobs, or front climate control panel itself are not operating properly, the problem may be with the FCIM/front control panel rather than the A/C Control Module.

Step 2: Check Battery Voltage and HVAC Fuses

Low voltage or a blown fuse can prevent the climate control system from operating correctly.

• Verify the battery and charging system voltage are normal.

• Check the applicable HVAC, blower motor, A/C, and climate control fuses and relays.

• Test fuses with a meter or test light rather than relying only on a visual inspection.

Step 3: Inspect the A/C Control Module Connections

Verify all connectors at the repaired module are fully seated and locked.

Inspect for:

• Bent or damaged pins

• Corrosion or moisture

• Loose terminals

• Damaged wiring

• Connectors that were not fully reinstalled

A poor connection can cause the same symptoms as a faulty module.

Step 4: Verify Power and Ground

Confirm the A/C Control Module has the proper power, ignition voltage, and ground.

A weak power supply, excessive voltage drop, or poor ground can prevent the module from properly controlling the HVAC system even when the module itself is functioning correctly.

Step 5: If Fan Speed Still Does Not Respond

If the fan or blower still does not operate correctly, inspect the vehicle-side blower system.

Check the:

• Blower motor

• Blower motor relay

• Blower motor speed controller/resistor

• Related connectors and wiring

A failed blower motor, speed controller, relay, or wiring problem will not be corrected by repairing the A/C Control Module.

Step 6: If Temperature Still Does Not Change

If the requested temperature changes but the air remains hot or cold, inspect the blend door actuator and HVAC door assembly.

Check for:

• Failed blend door actuator

• Damaged actuator wiring or connector

• Stripped actuator gears

• Stuck or binding blend door

• Broken HVAC door or linkage

A mechanical HVAC door or failed actuator can prevent temperature changes even when the A/C Control Module is operating correctly.

Step 7: If the System Operates but the Air Is Not Cold

If the controls and blower respond normally but the vehicle does not produce cold air, the problem may be elsewhere in the A/C system.

Check the:

• Refrigerant charge

• A/C compressor operation

• Compressor clutch

• A/C relay and fuse

• Pressure sensors/switches

• Related A/C wiring

These are separate from the internal electronic faults addressed by the A/C Control Module repair.

Step 8: Scan the HVAC System for Fault Codes

If possible, use a scan tool capable of communicating with the Ford HVAC/climate control system.

Check for stored HVAC-related fault codes and compare commanded functions with actual operation. This can help determine whether the problem is with the control panel, wiring, blower system, actuator, or another vehicle-side component.

Step 9: If the Issue Persists

If the module has proper power and ground and the wiring, blower system, actuators, and related HVAC components all test correctly, further vehicle-side diagnosis may be necessary.

Do not open or disassemble the repaired A/C Control Module. If you are still experiencing the original repair-related symptom after completing these checks, contact UpFix for additional assistance.