Skip the auto shop - Our mechanics make house calls

Q: What can cause heater to start blowing cold air and temperature to get really hot?

asked by on

I warmed up car this morning and we left. Then I had to wait 20 mins for school bus with car running and temp stayed normal. I got about 3 miles down the road and started up a steep hill when I noticed the heater was blowing cold air and car was very hot. I pulled over and turned off ignition. Could hear the gurgling noise a hot car makes and smell it was hot. Nothing had leaked out from it and I know it has antifreeze in it.

My car has 176785 miles.
My car has an automatic transmission.

Generally when the engine temperature climbs and the heater airflow turns cold, coolant has stopped circulating throughout the system. This can be due to a few things. The thermostat may have failed and is restricting coolant flow. The water pump impeller may have separated from the pulley shaft internally. The water pump can appear to be turning on the outside but the impeller may not be turning on the inside. Have the overheating condition checked immediately as continued driving can severely damage the engine.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  • Home
  • Questions
  • What can cause heater to start blowing cold air and temperature to get really hot?

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: Idling high

There are a couple of possible causes for a high idle. The most common is a Vacuum leak, which allows excess air into the intake causing the computer to read information improperly. Other causes are exhaust leaks, or various sensors...

Q: Can't stop when pressing the brake pedal

It sounds as though your brake booster, which facilitates power assist, is not operating. The brake booster operates from the engine vacuum; if the engine vacuum is leaking somewhere, then the power assist will not work, and your engine will...

Q: Car won't start - 2004 Nissan Xterra

This sounds like a potentially failing starter solenoid. As you may know, the starter solenoid is located on the starter and has internal electrical contacts that transmit electricity to the starter. When this fails, it may cause a clicking sound...

Related articles

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...
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.