Q: Heater works intermittently, when not working car overheats and thermostat is new

asked by on

The car is overheating. I replaced the thermostat. The fans are working. I have flushed the radiator. The water pump seems to be working. The car runs a normal temp at idle and low speeds. It only gets hot once it's run at 50-60 mph. The heat isn't working consistently though. When the heat works the car will cool down a bit, but as soon as the heat stops working it gets hot immediately. Any tips would be greatly appreciated. I'm good with basic car repairs, but I haven't seen this before.

My car has 261000 miles.
My car has an automatic transmission.

Hi there. In most cases, when you have issues with the heater working and the vehicle overheating, it’s caused by an obstruction of coolant inside the heater core. The cooling system circulates hot coolant / water into the heater core to heat the elements and blow warm air into your vehicle. If there is debris inside the heater core coolant tubes, it will have difficulty completing the circuit through the entire cooling system and cause overheating issues. The best way to know for certain what is causing your overheating problem, have a professional mobile mechanic come to your location to complete a car is overheating inspection.

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 works intermittently, when not working car overheats and thermostat is new

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: Car won't accelerate randomly when sitting in traffic, no change in engine performance, just won't go for 3 to 4 seconds

There was a Nissan recall in 2009 for your model year (2006) relative to an air intake fault. Be sure your vehicle was either not included in the recall or, if included, that it was serviced as this particular recall...

Q: Car has pick up problem

Hello. It seems like your vehicle is having performance related issues due to a fuel problem. A few things I would check are the fuel pressure regulator, the fuel lines, and the coolant temperature sensor. An issue with any of...

Q: Check engine light with a code about insufficient temperature P0126 to the engine.

Hi there. The coolant temperature sensor (CTS) is not working correctly. The sensor is sending a signal that the engine is already warm and when the engine first starts up, it needs more fuel a rich mixture to produce more...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.
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.