Only blows out defrost?
Thread Starter
Joined: Mar 2007
Posts: 1,698
Likes: 3
From: NE Pennsylvania
Car: 85 Iroc-Z
Engine: 383 TPI Procharger D1SC
Transmission: TKO600
Axle/Gears: Strange S60 3.73
Only blows out defrost?
When the heat is on in my car, the air only comes from the defrost vents no matter what setting you have it on. What could cause this?
Member
Joined: Dec 2002
Posts: 373
Likes: 0
From: Brooklyn, MI
Car: 1991 Camaro RS
Engine: 355
Transmission: 700-R4
Axle/Gears: 4.10
Re: Only blows out defrost?
Vacuum leak. The vents are conrolled by a vacuum swith behind the HVAC controls in the dash. You either have a leak in the lines or no vacuum coming to the switch.
Joined: Sep 2004
Posts: 5,906
Likes: 240
From: Chicagoland Suburbs
Car: 1989 Trans Am GTA
Engine: LT1, AFR 195cc, 231/239 LE cam.
Transmission: M28 T56
Axle/Gears: 3.23 10bolt waiting to explode.
Re: Only blows out defrost?
You have lost vacuum to the HVAC controls. Either it was unplugged from the engine/control, or its broken somewhere. It comes out of the firewall about a foot down near the passenger head.
Joined: Aug 1999
Posts: 19,282
Likes: 103
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: Only blows out defrost?
The problem is common to our cars (defrost is the default), and as a consequence, a search will provide a wealth of info on the subject.
JamesC
JamesC
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