Skip the auto shop - Our mechanics make house calls

Q: Heater blows cold.

asked by on

After using coolant leaking stopper 3 months ago, heater has blown cold weather. I changed thermostat, Flushed heater core radiator 2 times, and replace the coolant reservoir cap, but the issue never been resolved. The car does not get overheat and heating gage raised to the middle and stays cosistant untill turning off the car and getting cool down. When turning heat on there is hot blow for seconds and eventually dropt to cold one.

My car has 70000 miles.
My car has an automatic transmission.

A: Hi there. Leak stopper should only be used ...

Hi there. Leak stopper should only be used in emergency situations as it usually causes more problems than it "fixes". It sounds like the leak stopper may have settled in your heater core and is preventing the proper amount of coolant from passing through to provide heat inside the car. The only way to repair this is usually to replace the heater core and check the hoses for blockages and restrictions as well. There could also be a servo malfunction that has coincidentally surfaced. A visual inspection of the servo operation can usually identify a mechanical fault, but not an electrical fault. If you can gain visual access to the servo, turn the temperature to max cold then max heat and observe the movement. If the servo is moving both directions fully, then it is working and the fault is in the heater core. I suggest having a qualified technician perform an inspection to avoid replacing unnecessary parts. Your Mechanic has several technicians available that can assist you with a car has not heat inspection.

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

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 will not stay on.

Hi There, Code P0300 relates to a cylinder misfire. Engine misfires can be caused by many different problems and are generally caused by either a spark or fuel issue or in some cases, a combination of both. Spark related problems...

Q: I can not lock or unlock the doors on my 2010 Cadillac SRX

Hi there. Although your Cadillac is a rather complex vehicle, the power door lock system is a relatively simple system. When you press the lock or unlock button (located on your key, or inside your vehicle), the power door lock...

Q: Four-wheel drive encoder motor not working properly.

Hello, Since this recurring regularly the vehicle should be scanned for code. There is a good chance that the wiring to speed sensor on the transfer case has become compromised over time and the wiring harness needs to replaced. This...

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 Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
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...