How to Tell if a Car's Heater Coil Is Bad

Antifreeze runs through the heater coil to the rest of your vehicle. A faulty heater coil will not allow the antifreeze to pass through the car properly. If the antifreeze does not pass through the coil, the heating system will not operate. The heater coil is difficult to locate behind the dashboard to check for any problems. It is best to look for signs of a faulty heater coil first.

Step 1 – Signs of Antifreeze

Check the interior of your vehicle for any signs of antifreeze. The signs can be a sweet smell when the heater is in operation or a puddle of antifreeze in the passenger foot well. Signs of antifreeze indicate that the liquid is not running through the heater coil.

Step 2 – Signs of Vent Problems

Check for puffs of smoke coming from the ducts and fogging of the wind shield when the heater is running.

Step 3 – Signs of Radiator Problems

If the radiator has fluid and the thermostat is operating properly, there should be heat produced in the vehicle. If there is no heat, the heater coil is faulty.

Step 4 – Signs of a Cold Engine Block Hose

Turn on your vehicle and give it time to heat up. Open the hood while the engine is running. Carefully touch the two hoses running from the core to the engine block. A cold hose is an indication that there are problems with your heater coil.