Problem with defroster
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Joined: Mar 2008
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From: Franklin Ohio
Problem with defroster
I have a 88 Vette. When I press the defroster button on the Auto Climate Control Unit, the AC clutch engages and I get cold air coming thru the defroster vent. I have tried running the temp setting at 60 and at 90 degrees. Still, the same deal... I just put a brand new AC Heater programmer in the car. Still, the same deal... I looked at vacuum lines and they seem to be fine and there is plenty of vacuum. I have no idea what to look for at this point. Has anyone run across this problem?
Team Owner
Joined: Jan 2003
Posts: 20,318
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From: Summerland B.C. Canada
Which are you considering a problem, the cold air or the fact the compressor is running ?? The latter is normal, cold air, could be the blend door motor.
http://members.shaw.ca/dankai/AC%20Electronic.pdf
http://members.shaw.ca/dankai/AC%20Electronic.pdf
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Joined: Mar 2008
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From: Franklin Ohio
Agent 86.. I consider the fact that the clutch on the AC compressor starts running when I hit the defroster button on my Auto Climate Unit in my 88 Corvette. It blows out cold air because the AC is running... So, it would take that much longer for the windshield to thaw out. I have no idea what to look for now. I did change the programmer in the car. I checked the vacuum lines. Is there anything else that I could look at to find the problem? I would appreciate any further input.
Safety Car
Joined: Jul 2004
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i've an 88......check all vac lines again...check linkages on blend door motor arm at BOTH ends....check vacuum "t" at firewall in the engine compartment at/near drivers valve cover and distributor to the passenger side of the brake booster (vacuum is feed from plenum)...BEFORE you do any of this, disconnect battery for a few minutes and try again....
Last edited by Da Mail Man; May 8, 2008 at 06:51 PM. Reason: spelling error
Le Mans Master
Joined: Jul 2007
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From: No HOA, New Hampshire
Cruise-In X Veteran
St. Jude Donor '09
Dumb question from me, Did you let the engine warm up to pass the coolant past the thermostat? The reason I ask, is that the vacuum controls divert the air to the right place and the A/C conpressor comes on is normal. The heat door opens and heats the air after the A/C coil. The A/C system will not cool the air if the ambiant air is cold enough to frost the windshield. I may be missing something.
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Joined: Apr 2008
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From: Gainesville FL
Which are you considering a problem, the cold air or the fact the compressor is running ?? The latter is normal, cold air, could be the blend door motor.
http://members.shaw.ca/dankai/AC%20Electronic.pdf
http://members.shaw.ca/dankai/AC%20Electronic.pdf
100%. Mine's a '94, but I took apart my blend door motor and got it to work last year. It looks like a servo motor and worm gear. Good luck
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Thread Starter
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Joined: Mar 2008
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From: Franklin Ohio
pkazr.. I believe that there is a 195 degree thermostat in there, right now. I plan on replacing it with a new 160 degree thermostat. It might be that the old thermostat is worn out and not opening up quickly enough.