Q: Overheating issue, when heater is on its normal temp. but if heater is off it begins to overheats, until heater is turn on again.

asked by on October 03, 2016

When driving, car over heats, but if I turn heater on, temperature eases back to normal, and is good to go unless I turn heat off again. Even when in idle doesn't run hot with heater on, but if heater is off it over heats.I put new water pump thermostat radiator degas bottle and cap heater control valve and bled it several times

My car has 200000 miles.
My car has an automatic transmission.

Car is overheating Inspection $79.99 - $99.99 Get a Quote

It sounds like your engine might have a restriction in the cooling system. If the cooling system has a restriction that prevents its flow, this will cause the engine to get hot. The heat is dissipated from the cooling system by means of the radiator.

When a restriction exists sometimes the radiator alone is not enough. The heater core is like a small radiator inside the dash and is also another means of dissipating the heat from the cooling system. So essentially when the heat is on you are introducing a second radiator into the system which will help to cool the engine down.

In order to get this fixed, consider YourMechanic, as one of our mobile technicians can come to your home or office to diagnose the overheating issue firsthand and help you make the necessary repairs.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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


Experienced Mechanic?

Earn up to $70/hr

What others are asking

My car starts and runs perfectly fine when its the first time I turn it over that day. After I drive it for maybe a quarter mile to a gas station, I turn it off, pump gas, and get back in. After I turn the car on again and put it in gear, it'll stall out. Then I try to kick it over again, and this time if it doesn't stall again, it goes to a very low idle, almost stalling, and then it jumps. Then it fixes itself

Could a data read error for the oil pressure and sensor cause Smoke from tail pipes?

The smoke is unrelated to the issue you describe with the PCM. Some smoke at start up can be normal, particularly white smoke from condensation. However, continuous smoking after the first few minutes signifies a problem with the engine that...

my car idles up and down while sitting and die out fault code p1172 p1611 circuit short to ground p0507

Hi there. Due to the fact that multiple fault codes are showing up, I'd recommend having a professional mobile mechanic come to your location to complete a check engine light inspection; so they can pinpoint what is causing each code...

transmission axle has play or movement.

Hi there. The axle play could be caused by the outer bearing on the transmission to be worn out. The bearing is inside the transmission, so to replace the bearing, the transmission will have to be removed from the vehicle...

Car has been misfiring 2007 Mercury Mountaineer

Hello - first task is to check for problem codes, whether the Check Engine is lit or not. If it is, there should be an indication of which cylinder is misfiring. Misfiring can be ignition related - plugs, coils, timing...

Driver's side CV joint noise

Hi there. The sound is more like a differential sound that is making a click sound. There seems to be too much free play on the gear train inside the transmission. This is determined by only the sound occurring when...

Steering wheel shakes when applying brakes

The rotors and pads should be replaced as a set. If not, then you will not have even wear and diminished brake stopping power until the two components are seated to one another. Sometimes cutting a rotor will not...

Grinding noise and overheating while driving.

It could be that the grinding noise you were hearing was the water pump bearings. Engine overheating can do extensive damage to your engine. I suggest you have a trained mechanic, such as one from YourMechanic, diagnose or repair your...

Related articles

A Buyer’s Guide to the 2012 Lexus LS 600h L
The The “h” stands for hybrid, and while you might hope to get greatly improved gas mileage for your effort to go green, that shouldn’t be your motivation for buying this model. The 600h L offers a mere 1 mpg...
The Best Tool to Find Coolant Leaks
Diagnosing a car issue can be a tricky without proper tools. A coolant pressure tester is useful for diagnosing overheating issues and coolant leaks.
How Long Does a Water Pump Last?
The engine in your car produces a lot of heat, which means that the cooling system in your car will need...