Why does my car heater only work when I'm driving?

I have a GMC Yukon that’s been a workhorse for me for years. Until recently, it’s never had any issues. But as soon as the temperature dropped this winter, my heater started acting up. Why does my heat not work unless I’m driving?

Eric Schad · Updated on
Reviewed by Shannon Martin, Licensed Insurance Agent.
I’m glad to hear that your
GMC Yukon
has been great to you! If your car heater only works when you’re driving, it could be due to a number of issues:
  • Most commonly, you probably have low coolant. The coolant regulates many things in your vehicle, and your heater is one of them.
  • Air pockets within your cooling system might make your heater work erratically, as they cause poor circulation of coolant.
  • A faulty heater core could prevent your heater from working while idling. If the core is filled with debris, heated coolant can’t pass through the heating system.
  • Debris and corrosion can cause your thermostat to function improperly. When the thermostat is stuck in the open position, your engine doesn’t warm up to the proper temperature and your heater may not function correctly.
In most cases, proper maintenance can resolve these issues—whether you do the work on your own or take your car to a mechanic. Regularly top off your coolant, as this is the most common problem resulting in a failing heater.
Since you clearly love your Yukon, don’t leave it unprotected. Instead, use the
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Jerry partners with more than 50 insurance companies, but our content is independently researched, written, and fact-checked by our team of editors and agents. We aren’t paid for reviews or other content.

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