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Defrost blowes hot air even when turned off

When traveling I will have my 1986 G20 with the heater/defroster fan in off position but will get a stream of hot air coming into the cabin. I have removed the fan fuse and ruled it is not the fan becasue if I'm idle then I get nothing but as I move the hot air comes into the cabin either thru the defrost vent or heater vents depending on where I have the switch at.

In 90 degree heat it makes the cabin hotter and the a/c is not strong enough to cool both the cabin and additional hot air coming into the cabin.

Where should I start to look?

Thanks in advance for all the help you may give.

Reply to
Gary
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The passenger compartment of modern vehicles have a constant flow of outside air to freshen the inside air, and this comes through the heater or defrost vents. That is why you only feel it when moving. To stop this, try putting your AC on recirc and make sure that you have the fan on. If the fan is off, the flow of air from outside to inside will continue.

Reply to
Mark Schooley

will have my 1986 G20 with the heater/defroster fan

That would be fine but A/C and Heater use two different vents - really wouldn't call a 1986 model vehicle modern - would think there would be a way to stop hot air from coming in the cabin - otherwise on a 90 degree day you would be driving in a vehicle that is 120 degree - and that would be unsafe as you could pass out from heat exhaustion. I know my car (2001 model) does not do this - just don't know where to go to find the part that is broken.

Reply to
Gary

I had a similar problem on a '87 G20. It was a vehicle we used on the property. Turned out the 'temperature mixer' door cable was broke. The door was in the 'hot' position. It really wasn't worth fixing in our case. You can reach up under the dash on the passenger side & feel around for the lever. In the summer we positioned the lever in the 'cold' position and in the winter we moved it to the 'hot' position. Maybe yours is stuck in the hot position.

James

Reply to
James1549

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