Q: Heating unit makes my temperature gauge go up

asked by on

Car runs well but when I run the defroster or try to warm up the inside of my car the tempurere gauge goes to the over heating side when I turn off the heating unit gauge goes right back to normal and car runs well
My car has an automatic transmission.

Hi there. It sounds like there could be the possibility of a low cooling system level. Check the level when the engine is cold and add as necessary. When you turn the climate controls to heat the inside of the car, coolant is diverted to the heater core to use the heat in the coolant to warm the air as it passes over. If this is producing an unusually low level in the cooling system, the coolant temperature sensor may act erratic as it would trying to measure temperature of a limited supply of coolant. Note that air heats faster than water and the sensor could be reading the air in the system.

I strongly suggest acquiring a qualified technician to perform an inspection and avoid replacing unnecessary parts. YourMechanic has several technicians available that can assist you with a cooling system inspection and provide an estimate and direction of 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. Heating unit makes my temperature gauge go up

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 overheats only at low speed

Hello. It is possible that the water pump is not pumping properly or that the radiator has a partial clog which is causing the car to overheat at low speeds. Have a certified technician, like one from YourMechanic, complete an...

Q: My power steering fluid keeps draining and needs refilling

It sounds like you have a significant leak based on the rate of fluid loss. There is probably external evidence of the leak; it is also possible to have multiple leak points, of course, particularly as the car ages. However,...

Q: Rough idle code p0191 and p0304

Hi There, As you may know, code P0191 relates to the fuel pressure in the fuel rail. When the PCM detects that the fuel pressure is not what it should be this code will be triggered. This may be related...

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 Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...