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9/28/08 12:44am - Original Message: 'Defrost Control'
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mount airy, MD - USA

1981 Charcoal Met., Silver Interior, Gymkhana Suspension, 27K original miles. It's my daily driver.

Joined: 8/27/2006
Posts: 71
Took the car out today for the first time since getting it 2 weeks ago. 1981, 27K original miles. When I looked at the car before purchasing,  the heat and defroster vents wprked fine when moving control back and forth. today when I went to use the defroster it didn't blow out through the defroster vent but blew onto floor. After driving a few miles it finally started coming out through the correct vents. Is this just due to the fact of the low mileage and not much use or is there something else I should be looking for?  This is only my second 81' and i'm still learning some of the little things about these cars. Thanks, Tom  

1981 Corvette, 26K original miles, charcoal gray, gymkhana suspension, AM/FM/8 track.
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9/29/08 12:11pm - Reply: 'Defrost Control'
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Mounds View, MN - USA

70 LT1 coupe, 69 350 HP coupe, 69 390HP 427 coupe, 71 LS5 convert, 85 coupe, 93 coupe

Joined: 5/24/2007
Posts: 1031
Low mileage cars tend to have a lot of things kind of sticky.  If you drive it a bit and it frees up, great, but if not you might need to take things apart and clean and silicone the flaps and actuators.  There is an A/C vacuum diagram available that might be of help.  I remember finding it on the internet, but don't remember where.


Corvette Specialties is your best source for Corvette parts, accessories and gifts. www.CorvetteSpecialties.com


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9/29/08 2:04pm - Reply: 'Defrost Control'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19511
It's also possible the vacuum control switch has dried out over the years, and not allowing the vacuum to get to the appropriate servos to move the mode doors/flaps. Any small vacuum leak anywhere on the car will effect the operation of the HVAC system, too, so check around under the hood, and under the dash for any tell-tale hissing with the engine running, that would suggest a vac. leak.

As Larry says, it might just need some working out to get it all limbered back up, too. Hopefully, that's all it needs. Work it back and forth a few times to see if it improves.

Joel Adams
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 Forums -> C3 Cooling and Heating Systems
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