What could be wrong with my car's heater?

Question

When I have the temp switch on my car set to cold and the fan set to high I get a lot of air flow out of my dash vents but as soon as I turn the temp switch to hot the air barely comes out of the vents. I don't hear any change in the blower motor. I can switch it back and forth from hot to cold with the same results. Same thing when I have it set to defrost or floor. The air that comes out when it is set to hot is warm but if you move your hand more than 2 inches from the vent you feel nothing. Same thing if I run the fan on other settings - more air flow when set to cold than when set to hot.

Update:

It is a '93 Pontiac Firebird.

franklinbud8 · Accepted Answer

What kind of car is it? Sounds like you may have debris  (such as leaves) blocking air flow thru the heater core, older gm's were bad for this. Would'nt be a pontiac would it??

Ret68 · Answer

This may be a long shot but, I had a vehicle once that did exactly what you describe. What I found was that the foam that was attached to the blend door had come loose and when the blend door was moved to divert the air through the heater core it couldn't get through the heater core because the foam backing had the opening covered up... Just A thought... Good Luck...

ben27hernandez · Answer

your car has like little doors that open certin  when you move the (lever/nob) depening on make and model of the car. one or a couple of the doors could be getting stuck. Also you could have a blockage. your heater core could also be going out.

oldster · Answer

Sounds like a heater core.

Anonymous · Answer

most cars use vaccum to operate the heater doors.check the vaccum to see if you got any to the actuators,that opens the doors.also check the cables.

slp9209 · Answer

sounds to me you have a vacume leak it is not letting the window open and close to send the air to where it should go

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What could be wrong with my car's heater?

6 Answers