Q: Overheats when heater is on, heater blows cold air.

asked by on

I just had the heater core bypass hose assembly replaced two weeks ago due to a very bad leak. Car was running fine after the repair, no temp problems, until I turned the heater on today. Within five minutes the temp gauge was almost all the way up while the heater was still blowing cold. The heater used to work great before the repair, save for a slight coolant smell when turned on. Now it blows cold while the motor overheats! That's the opposite of what I need!

My car has 233000 miles.
My car has an automatic transmission.

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. Overheats when heater is on, heater blows cold air.

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: Put new battery in my car

Hi Tiffany. Thanks for writing in to YourMechanic.com today. Corrosion is caused by oxidation, and battery acid leaking - which occurs overtime. It can create a faulty ground or power connection and cause several of the symptoms you are describing....

Q: Heat turns cold after I drive for awhile. Got the water pump changed and the thermostat. Still having issues

If the cooling system gets low at all, usually the first thing you notice is that the heat goes away. The system could seem to be full, but have air pockets causing your problem. That can be solved by bleeding...

Q: My transmission was rebuilt 6mos ago, overdrive light blinking

Hi there. The overdrive light flashing is, the time a fault is recognized by the PCM (Powertrain Control Module) and/or TCM (Transmission Control Module). The fault code for the overdrive problem should store in the computer's memory. This should help...

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...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...