Why Isn’t My Car’s Heater Working?

October 24, 2017

car heater broken brrrCold and freezing temperatures will be hitting most parts of the country within the next few weeks. Before that happens, it would be wise to check your car’s heater to confirm that everything is working properly. By doing this now, you’ll be giving yourself enough time to tend to any required repairs before winter temperatures make it necessary to drive with the heater running.

If there is a problem with the heater, here are some likely causes to check out in case you’re inclined to tackle the repair on your own.

If your car heater is blowing cold air:

  • Check the coolant level to make sure it isn’t too low. If there’s not enough coolant, it won’t be able to circulate through the heater matrix properly, which results in the system blowing out cold air instead of warm. The solution here is to top off the coolant and try again.
  • Check to see if you have an air lock in the system. Is one heater hose hot while the other one is cold? Does your vehicle’s temperature gauge move up and down rapidly? Is your temperature gauge consistently reading high to indicate an overheated engine? These are all signs of a possible air lock in the heating system, so try bleeding the coolant by following procedures for your vehicle make and model.
  • Check to see if your thermostat is broken. A broken thermostat typically causes a car to overcool and prevents the heating system from producing warm air. To fix this problem, you’ll have to replace the thermostat.
  • Check that the heater control valve is intact and functioning. The heater control valve (or flaps in older cars) is responsible for channeling warm air into the vehicle cabin. If it’s not working correctly, the warm air will be misdirected. A broken or malfunctioning heater control valve should be replaced as soon as possible.

If your car heater isn’t blowing any air at all:

  • Check that the blower motor is receiving power. If it is receiving power but still isn’t working, then it’s likely burned out and needs to be replaced.
  • Check the blower fuse, relay, resistor, and switch. If the blower motor is not receiving power, then the problem can usually be traced to a blown out fuse or a faulty relay, resistor, or switch. Once you identify which part is causing the issue, you can replace it.

These are just some of the possible reasons why your car heater isn’t working. If you look at all of these elements and still can’t pinpoint the source of the problem, take your car to a certified mechanic for a more thorough diagnostic inspection.

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