Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Heating cuts out

I’ve got a Chevy Malibu 2001 with 111,000 miles. Haven’t had too much trouble with it (at least not as much as others I’ve read about).

I’ve got a problem when I’ve been driving the car on the interstate for about an hour and a half and the air stops blowing from the vents. The fan is still running and I can feel a little heat, just nothing blowing. After another 30 to 45 minutes, the air flow comes back on. I’m guessing there’s a sensor somewhere that heats up and shuts down the air flow, then once it cools off it allows the air to flow again.

The thermostat is rock solid in the sweet spot on the dash, so that doesn’t seem to be acting up. Driving around town it is fine and it only seems to be the heat, not the cooling.

Thanks for any help!

Airflow is controlled by various flaps, or doors, in the HVAC system. These are operated either by electric motors or vacuum actuators. If there is a problem with a motor or an actuator, the airflow can be interrupted, or it may come from the wrong vents.

It sounds like one of the flaps is moving when it shouldn’t, and directing the air to the wrong place. When this happens, does warm air come out ANYWHERE?

It doesn’t seem to come out anywhere. Vents, floor, defrost…nothing…

There is something else going on with the flaps and it deals with when I hit the recirculate button. Sometimes it just decides to go back to outside air. It does it more when it gets cold outside. I can hold the recirculate button down and after a few minutes it will stay in that mode (or the car warms up enough for it to stay). But at any time it will decide to pop back into outside air mode.

On most GM products the flaps for the heating and A/C are controled by vacuum, and it appears you may have a small leak in that system. This is usually noticable when you accelarate.

There is no sensor which controls this.

To keep my wife’s feet warm, I was thinking of using a cigarette power converter to plug in a heating pad. Would that cause too much strain on the electrical system? We would use it on low settings and not high heat. Thoughts?