HVAC Issues - 1995 Convertible Corvette
Forum: C4 HVAC, Fuel, Emissions, and Exhaust
I don't think that my HVAC system (air-conditioning or heating) on my 95 convertible corvette is operating properly and I'd really appreciate some feedback as to if this is how these systems are supposed to work.
AIR CONDITIONING
CRITERIA
1. Outside air temp = 85 degrees +/-.
2. Air temperature at vent = 41 degrees when set at 60 degrees and in re-circ mode.
3. I had a mechanic check the freon and he confirmed that the system had the correct amount.
4. When I select the auto or bi-level modes, after about 15 minutes of operation water will begin to condense on the outside of the windshield just above the defrost vent. I actually built a temporary deflector to keep the air off of the windshield when I'm trying to cool the cabin.
5. Air appears to discharge from the correct vents respective to the selected mode. This applies to both the ac and heating system.
ISSUE
At the 60 degree setting in re-circ mode, the cabin won't get close to being cold like the cabin of my 2002 Chevy Impala or other cars which will freeze you out if you leave it there for very long. My system never gets the cabin so cool that I've got to turn it up even after driving for an hour or more and with the air temperature at the vents being 41 degrees. No matter which setting (auto, re-circ. or bi-level) that I've selected, the system can't begin to keep up with the heat. Also, I've had a friend of mine listen to hear if the fan goes to a higher speed when switched from auto to re-circ but we didn't hear any difference.
HEATING
CRITERIA
1. Outside air temp = 30 degrees +/-.
2. Air temperature at vent when set to 85 degrees will be about 76 degrees. This isn't enough to keep me comfortable at these outside temperatures nor is it enough to allow the defroster to clear the entire windshield.
3. Air temperature at vent when set to the next higher setting (90 degrees) is 141 degrees. This will absolutely boil me out and I'll have to cycle back down to the 85 degree setting.
4. I replaced the heater core November of 2009 but it didn't change anything.
5. I replaced the thermostat with a 180 degree LT1 specific thermostat from the dealer 64,000 miles ago.
When it's cold outside I don't get hardly any heat unless I cycle between the 85 degree setting and the 90 degree setting.
I'd love to be able to set the cabin temperature to the temperature that I want in any mode and have the system just do it's thing, just like any other Chevy. I'm tired of not getting cool enough or having to cycle back-and-forth for heat during the winter.
Any help would be greatly appreciated.
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THE DYNAMIC DUO
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don't remember the technical name but its something to that effect. hvac controller maybe. could be in the electrical section. ran codes on mine a while ago and it said inside temp sensor was bad but the fan varies the way it should. after the problems i have (mainly the accident), i haven't had the chance to mess around and find the box behind the dash. right now it is on my to do list.
THE DYNAMIC DUO
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It sounds to me like you may have a problem with one of the doors in the plenum not closing properly, but that may well be due to a problem with the controller/"programmer". 40* air coming from the vents should eventually cool the interior, but you gotta remember, there is a large expanse of glass in these cars, especially if you have the glass roof panel. Even without the glass roof, the rear hatch glass, and the angle of the front windshield creates what is basically a hothouse.
In my '85, I have to keep one of the windows down about 1/2 inch for 10 minutes or so(while driving) with the A/C on HIGH in order to let the superheated air out of the cabin. Otherwise, it will take forever to cool the interior.
IF there is not a problem with the controller, then it may be that the ducts are not sealed well, or there may be some foreign matter stuck in the plenum/ducting that is keeping the door(s) open when they should be closed, or versa-visa. It may come down to one of the doors simply being out of adjustment, too. The FSM should have the info on how to check/adjust all of the doors.
Joel Adams
C3VR Lifetime Member #56 
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(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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THE DYNAMIC DUO
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DOH! 
Dang...missed that!
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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THE DYNAMIC DUO
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