1. Blend Door Actuator: This is the most common cause of clicking noises in car A/C systems. The blend door actuator is a small motor that controls the direction of air flow (e.g., vents, defrost, floor). If it's failing, it can make a clicking sound as it struggles to move the blend door.
* Troubleshooting: Try changing the air direction settings (vents, defrost, floor). If the clicking changes or is most pronounced during these shifts, the blend door actuator is a strong suspect. You might even feel resistance when manually trying to change the air vents if it's severely seized.
2. Blower Motor Resistor: This component controls the fan speeds. A failing resistor can cause clicking, especially when changing fan speeds.
* Troubleshooting: Try changing the fan speed. If the clicking is linked to fan speed changes, the resistor is likely the problem.
3. Relay: Relays are electrical switches that control the flow of power to various components. A failing relay can cause intermittent clicking.
* Troubleshooting: This is more difficult to diagnose without a multimeter to check for proper voltage and continuity.
4. Wiring: Loose or damaged wiring within the console can cause intermittent electrical connections and clicking sounds.
* Troubleshooting: This would require inspection of the wiring harness within the console. This is usually best left to a professional due to the complexity and safety concerns related to working with automotive wiring.
5. Other less likely causes: While less probable, a failing component in the AC system itself (like a compressor clutch engaging and disengaging improperly) *could* sometimes manifest as a clicking sound heard near the console, though typically the sound would originate closer to the engine compartment.
What to do:
1. Listen Carefully: Try to pinpoint the exact location of the click. This will help narrow down the possibilities. Is it definitely coming from *inside* the console, or perhaps slightly further back?
2. Observe the A/C Operation: Pay attention to whether the clicking is related to specific functions like fan speed changes, temperature adjustments, or air direction changes.
3. Check Fuses: Ensure all related fuses are intact.
4. Professional Diagnosis: If you're not comfortable diagnosing electrical issues, it's best to take your Expedition to a qualified mechanic. They have the tools and expertise to diagnose the problem accurately and safely. Attempting to repair the blend door actuator or other components without experience can potentially cause further damage.
The blend door actuator is the most likely culprit given the symptoms, but a professional diagnosis is always recommended before undertaking any repairs.
