How do you repair a car heater?

In order to repair a car heater, diagnose the problem, troubleshoot that part of the system and replace the component. There are many issues the can cause the heater to malfunction, so a diagnosis must first be completed, prior to replacing any components.

The heat system must first be diagnosed with a problem, as it can stop working due to a faulty thermostat, blender door actuator or even the core itself. Listed below are two sets of instructions that explain how to repair common issues that can occur inside the heating system.

Heater Door Actuators

1. Remove the vent cover

The vent covers are the plastic vents where the air comes from. Use a pry tool to remove them.

2. Locate the heater door actuator

The process of accessing the heater door actuator depends on the vehicle itself. However, most units are found behind the blower motor assembly. Use a repair manual to specify what components are required to be removed.

3. Loosen the actuator mounting hardware

Loosen and remove the mounting hardware for the actuator, then replace the unit.

4. Install the new actuator

Install the new actuator, replace the removed components and reinstall the vent covers. Turn the heat onto snsure it works properly.

Flush the system

The coolant lines may sometimes create air bubbles within the heating system. If this happens, the core will not receive the heat produced by the coolant, resulting in little-to-no hot air.

1. Drain the coolant

Locate the hoses near the heater core and place a pan under it. Loosen it and let the coolant flow into the pan.

2. Refill the coolant

Reconnect the hoses and pour coolant into the radiator.

3. Turn the heater on

Turn the heater and check if it works.