How to Fix a Vehicle’s Heater

A car heater just circulates some hot coolant from the engine through a device that looks similar to a small radiator resulting in the interior of the car to get warm. The main parts of a car radiator are the heater core known as radiator, blowing motor known as fan and the hoses.

To repair a car heater, just follow the simple directions:


Step 1:

Check the heater system to find any broken parts and blockages. Be sure that the hoses of the heater are in a good condition. If the car’s engine block has a summer valve, then make sure it is open.

Vehicle’s Heater

Step 2:

Inspect the motor and blower circuit if necessary. If the blower motor is not functioning, check all the switches, wire connectors and fuse. Some of the blower motors also have resistors that can burn and require replacement. An ohmmeter can be used for checking them.

Step 3:

If the blower motor needs replacement, consult the car service manual and follow the instruction for doing it. Some cases require the dashboard to be disassembled partly. The cooling system would have to be first drained.

Step 4:

Incase the heater core needs replacement, and then the instructions mentioned in the car service manual would have to be followed again. There are a lot of ways for doing it which cannot be covered here. A housing unit generally houses the heater core, it is either in the engine compartment against the firewall or under the dashboard. It has to be disconnected, disassembled, replaced and assembled.

Step 5:

For testing the car heater, the earlier procedure for buying ice cream has to be repeated, if it melts before returning home, the heater is working fine.

Additional Tips

  • An ohmmeter is a useful device, it measures the resistance in an electrical circuit. If there is an infinite resistance, then the circuit is open and will not pass electricity. An ohmmeter called a Volt Ohmmeter (VOM) can also be used because it will tell the amount of voltage present in the circuit.
  • The thermostat has to be changed when the heater cores are to be changed.
  • Be cautious when working with heater and radiator, coolant and hoses. They can be extremely hot. The radiator cap should never be opened when the engine is hot. Use of safety goggles is recommended.
  • Use gloves or rags to protect your hands, squeeze the radiator hose gently for checking the pressure before the radiator cap is opened.