My car does not heat, which is a big issue when the weather is cold. Nothing works and there is no heat from the AC. The face plate, which controls the heat outlet, doesn't function at all. It is unresponsive. I replaced the body control module as well as the heater box but it hasn't helped. I haven't found any wires that are worn or loose. Do you have any suggestions how I can fix this?
When you say the heater box, I assume you mean the heater core. If nothing happens on any temperature setting, the blower motor, blower motor resistor (which also houses the relay) or HVAC control unit may be faulty. The problem could also be in the blower motor control circuit wiring.
When you turn on your heat, AC, or vent, power flows through a fuse to the HVAC control unit, to the blower motor resistor and finally to the blower. If only the heater does not work, suspect cooling system issues such as faulty thermostat or air in the coolant. A failed blend door could also be obstructing heat flow.
A trained professional, such as one from YourMechanic, will be able to diagnose the heating issue in your vehicle firsthand.
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