Q: Heater gets hot but then blows cold when idling or driving.

asked by on

heat gets hot then cold when idle or driving i have changed thermastate and new coolant

My car has 45000 miles.
My car has an automatic transmission.

This may be due to a faulty heater blower motor or potentially a bad heater core. As you may know, the heater core is a small radiator like unit that circulates the hot coolant from the engine through the heater core which then uses this warm coolant to heat the inside of the car with the help of the blower motor that blows the warm air through the vents inside the car. To avoid any unnecessary repairs, I would still recommend having a certified expert, like one from YourMechanic, come to your location to diagnose your heater issue firsthand and make the right repair.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Heater gets hot but then blows cold when idling or driving.

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Horn/Chime will not sound when I activate alarm.

Hi there. Replacement of the struts should have no affect on the horn as there would have been no reason to remove any part of that system. First, does the horn work if you press the horn button? If so,...

Q: Oil in the coolant tank

Hi, thanks for writing in. If you have coolant in the engine oil showing on the oil cap, then you likely have a blown head gasket. The oil in the coolant is most likely from the blown head gasket getting...

Q: Window will only open, but not close

Hello there, thank you for asking about your 2003 Chrysler Intrepid. The power window motor is just a reversible DC motor, the direction of which is determined by the window switch. If the switch is OK, my guess is that...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.