Skip the auto shop - Our mechanics make house calls

Q: Heater blows cold air when vehicle is stopped.

asked by on

I recently got new head gaskets on my car, along with many other things like thermostat, plugs and wires, alternator. I drove it today after it was sitting in the shop for 2 weeks (I was getting new wires on it), and the heater blows out cold air when at a stop light. I just noticed it today. I got the head gaskets done about a month and a half ago, and didn't have any problems until tonight? My car isn't overheating, it simply just blows out cold air when stopped. It has been very cold here, and I didn't give it much time to warm up, so maybe that has something to do with it? However, I did drive for about 15 miles and it continued to blow cold air at stops.

My car has 134000 miles.
My car has an automatic transmission.

You may have a clogged heater core that may be prohibiting the outer linings of the heater core to get hot. As you know, the heater core is a series of tubes that the coolant runs through that generates the heat from the warm coolant after circulating through the motor. These tubes can occasionally develop a buildup on the inner walls such that when the heater core is "flushed" this buildup on the inner walls of the lines remains and still allows the coolant to flow through the heater core. It is important to note that when the heater core is "flushed" it is possible to get good flow through the heater core while the inside walls of the heater core remain caked with buildup. As a result, the buildup on the inner walls prevents the temperature from rising to its capability due to the insulating effect of this buildup on the inner walls which will prevent the necessary heat transfer to properly heat the inside of the car. I would recommend having an expert from YourMechanic come to your location to diagnose and replace your heater core.

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: When I shift from drive to reverse or vice versa it makes a clunking noise. 1997 Land Rover Discovery

Hi there - the clunking noise you hear from shifting forward-to-reverse (or vv), is the result of a small amount of wear and loose motion in the driveline. This could be a worn u-joint, differential gears, or splined coupling somewhere...

Q: How much to change front pads and rotors on disco II?

Billing question for the cost to replace the front brake pads on a 2002 Land Rover Discovery with a V8-4.0L engine.

Q: The engine stutters for a while before starting. 2002 Honda Civic

Hi there - if your car stutter-starts, but runs fine once it is running, you probably have a problem with the fuel system check valve. This valve maintains some fuel pressure in the system so that your car starts faster...

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 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.