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 1,000 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

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  1. Home
  2. Questions
  3. 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: My odometer reading is gone. How can I bring it back? 2013 Nissan Versa.

There should be a small button on the dash that enables you to change what is displayed on the screen. I would recommend pushing this button until the odometer comes back. If this does not work, it is possible that...

Q: My vehicle 2000 grand caravan. Wont shift into 2nd gear i have low when put in 3rd to try coming up through the gears it wont shif

Hello, thank you for writing in. When having issues shifting, the first thing you want to do is check the level of your transmission fluid. The hydraulic fluid is what allows the gears to be changed, and it is a...

Q: hello. I gave 2006 exterra. I put canned coolant in bu only last a couple of days. .do you think compressor is shot or p

I believe what you are referring to is refridgerant. Refridgerant is likely what you added to your air conditioning system. If this has been added and the cold air begins to blow again, it is likely not the compressor. If...

Related articles

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...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
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...