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Topic: HVAC Issues - 1995 Convertible Corvette

in Forum: C4 Cooling and Heating Systems


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HVAC Issues - 1995 Convertible Corvette (1/9)
 11/30/10 1:38pm
Freedom95
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Kansas City, MO - USA

Vette(s):
1995 Convertible Corvette


Joined: 11/30/2010
Posts: 3

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.

6. If I select the air temperature to anything less than the 85 degree setting I don't get hardly any heat. It's not enough to keep me warm or clear the windshield.
ISSUE
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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HVAC Issues - 1995 Convertible Corvette (2/9)
 11/30/10 8:52pm
eddie20890
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lanoka harbor, NJ - USA

Vette(s):
1990 L-98 white/ red/black leather interior targa top auto 1975 L48 blue/black leather interior t tops auto


Joined: 3/22/2009
Posts: 1363

there is a hvac module behind the dash. having a service manual is a big help too. it sounds as if that maybe out of whack.  could be the convertible not  holding temp (either hot or cold). the temp should not flucuate that much by one setting. in the service manual they tell you what buttons to press for the codes for that system.  some times mine screwws up and i cant shut heat off and i will have to shut car off and restart and sometimes just finicky when operating. let us know how you mak out.

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the dynamic duo


c3vr life member #97
HVAC Issues - 1995 Convertible Corvette (3/9)
 12/4/10 9:53am
Freedom95
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Kansas City, MO - USA

Vette(s):
1995 Convertible Corvette


Joined: 11/30/2010
Posts: 3

eddie20890,
Thanks for the info.   Is 'hvac module' the actual name of the item?   I do have the FSM for the car but it's not been a help troubleshooting these issues.   I'll run the hvac codes again but when I did the last time, nothing showed up.


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HVAC Issues - 1995 Convertible Corvette (4/9)
 12/4/10 5:09pm
eddie20890
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lanoka harbor, NJ - USA

Vette(s):
1990 L-98 white/ red/black leather interior targa top auto 1975 L48 blue/black leather interior t tops auto


Joined: 3/22/2009
Posts: 1363

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.



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the dynamic duo


c3vr life member #97
HVAC Issues - 1995 Convertible Corvette (5/9)
 12/5/10 12:03pm
Adams' Apple
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Duncanville, TX - USA

Vette(s):
1985 Coupe-L98/Auto,Bright Red/Carmine. 1974 Coupe-L48/4speed, Medium Red Metallic/Black Deluxe.


Joined: 3/18/2009
Posts: 2230

Fan speed will not change when going to "Recirc" or "Max A/C". The difference in perceived noise is the fresh air door closing, which makes the fan sound louder.
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.


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Joel Adams  
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

HVAC Issues - 1995 Convertible Corvette (6/9)
 12/5/10 12:19pm
eddie20890
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lanoka harbor, NJ - USA

Vette(s):
1990 L-98 white/ red/black leather interior targa top auto 1975 L48 blue/black leather interior t tops auto


Joined: 3/22/2009
Posts: 1363

joel has a lot of good points (as usual). even though you have a convertible and not the glass top, there still is a catch 22 problem. there is no insulation in your roof so the air can lose the cool/heat pretty quickly. try checking what joel said.

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the dynamic duo


c3vr life member #97
HVAC Issues - 1995 Convertible Corvette (7/9)
 12/6/10 9:10am
Adams' Apple
Standard Member
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Duncanville, TX - USA

Vette(s):
1985 Coupe-L98/Auto,Bright Red/Carmine. 1974 Coupe-L48/4speed, Medium Red Metallic/Black Deluxe.


Joined: 3/18/2009
Posts: 2230

[QUOTE=eddie20890]...even though you have a convertible and not the glass top...[/QUOTE]

dohDOH!

Dang...missed that!Confused


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Joel Adams  
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"

HVAC Issues - 1995 Convertible Corvette (8/9)
 12/6/10 9:18pm
eddie20890
Standard Member
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lanoka harbor, NJ - USA

Vette(s):
1990 L-98 white/ red/black leather interior targa top auto 1975 L48 blue/black leather interior t tops auto


Joined: 3/22/2009
Posts: 1363

you got lucky on this one joel. in either the convertible or glass tops, a problem with the hvac is a pain.Thumbs Up

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the dynamic duo


c3vr life member #97
HVAC Issues - 1995 Convertible Corvette (9/9)
 12/8/10 1:48am
Freedom95
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Kansas City, MO - USA

Vette(s):
1995 Convertible Corvette


Joined: 11/30/2010
Posts: 3

Guys,
Thanks for the info.   I'm going to check the hvac codes again tomorrow and will let you know what I find.   I ran them about 6 months ago and nothing came up.   Will poorly adjusted doors trip a code?
 
Is there another way to throughly have the programmer checked without spending big bucks and taking the dash apart?
 
Thanks again.


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