Heat from defrost but not vents
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From: Lake Village, AR
Car: 1992 Camaro RS 25th Anniversary
Engine: 305
Transmission: Auto
Heat from defrost but not vents
Happened all of a sudden today. I get heat from the defrost if I switch to it but if I switch it to vent, the air is cold/luke warm. My heat setting never has worked so I've always ran my heat on vent. Any ideas?
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Joined: May 2010
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From: Chickamauga, GA
Car: 89 IROC-Z
Engine: 355ci SBC
Transmission: TH700R4 - 2500 stall
Axle/Gears: 3.70 9 bolt
Re: Heat from defrost but not vents
Sounds like the vacuum line going to the heater valve may be disconnected or clogged. Mine does the same thing... though my vacuum lines are disconnected at the moment. But it blows through the defrost and won't heat. May want to check it and see if that hose came off. It's on the passenger side on the heater hoses.
Joined: Apr 2010
Posts: 405
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From: Montana
Car: '84 Firebird TA & '87 Camaro LT
Engine: 350 V-8 & V-6
Transmission: 700R4
Axle/Gears: 3.23 & 3.42
Re: Heat from defrost but not vents
Defrost is the default position. Check the vacuum switch, may be leaking
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Joined: Nov 2009
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From: Lincoln, NE.
Car: '87 IROC
Engine: 5.7 Vortec w/ factory TPI
Transmission: WC T-5
Axle/Gears: 3.45 Posi
Re: Heat from defrost but not vents
I had the same problem on my '85 Z28 back in the day and it was a bad vacuum switch in the HVAC controls.
Joined: Aug 1999
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From: Lawrence, KS
Car: Met. Silver 85 IROC/Sold
Engine: 350 HO Deluxe (350ci/330hp)
Transmission: T-5 (Non-WC)
Axle/Gears: Limited Slip 3.23's
Re: Heat from defrost but not vents
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