My Heater Wont Work!


All summer long you’ve been cranking the air conditioning or riding with your windows down!  As wonderful as summer is, fall is here and it’s time for cooling mornings and seat heaters!  As the weather cools down,  This year when you reach for the heat the first time will you get hot air?  Will you be greeted with that “first time you used the heat this year” smell?

If you turn on your heat and get cold air, there are 3 possible causes:

Why Your Heater Won’t Work

  • Broken Blower Motor
  • Broken Blend Door
  • Clogged Heater Core

The blower motor is the fan that pushed air through your heater core and if it’s not blowing you won’t get any heat.  If the blower motor has burnt out or the bearings seized it can cause the fan not to spin.  Another cause of your blower not moving air is if the fan is clogged.  This can happen from a clogged cabin air filter or from debris in the fan blades.

Another cause of a lack of heat could be a problem with your blend door.  The blend door directs air either over your heater core for heat or around it for cool air.  If the blend door is malfunctioning it could be causing the problem.  The air blend door is controlled either by a vacuum actuator or a servo motor.  If your car is relatively new the ventilation system may even be accessible by a scan tool which can tell you the state of the blend door and its orientation.  The most difficult problem to diagnose is if the blend door is mechanically broken or stuck as the only way to prove this is to inspect the door which is often hidden deep in your ventilation system.

The most common cause of a heater not working after a long summer is a clogged heater core.  If your vehicle has a shutoff valve in the heater hose then this can be even more likely.  The tubes of your heater core are some of the smallest coolant passages in your cooling system so it’s the most likely place for debris to collect.  If your heater core is clogged with debris coolant flow will be reduced which will decrease its ability to heat your car.  The best thing to do in this case is the flush your heater core to remove the debris to increase flow.

The best place to start is by removing heater hoses and forcing water both ways through the heater core.  This can be done using a garden hose or other pressurized water source and correct sized hoses.  Once you’ve mechanically removed any debris from the heater core, reattach the hoses then fill your system with water and BlueDevil Radiator Flush to chemically remove any remaining scale or contaminants that will reduce heat transfer and keep you cold this winter.

To purchase BlueDevil Radiator Flush, head to any of our partnering local auto parts stores like:

  • Advanced Auto Parts
  • Autozone
  • Carquest
  • Napa
  • O’Riley’s
  • Pep Boys
  • Walmart

Pictures provided by:

heater_core.jpg – By Yevhenii Orlov – Licensed By Getty Images – Original Link


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