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Engine Heat from Dash/A/C

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DaveMacGSP

Guest
I recenlty purchased a beautiful '75 Vette. One challenge, other than the A/C does not work, is that no matter what controls on the climate system I set, when I run it hard I get a lot of heat out of the vents. It doesn't take running it long at 60 - 70 miles an hour. I am aware of some heat barriers to go under the carpet, but I think I may have some problems with the ventalation system.

Thoughts?
 

6880 Mike

Well-known member
Joined
Jun 30, 2006
Messages
2,723
Location
The Bluegrass State
Corvette
1968 convertible; 1980 L-82
I would not be surpised to learn the hot water shut off valuve is stuck open allowing warm coolant to run continuously through the heater core. Might want to check it.

;)
 

minifridge1138

Well-known member
Joined
Feb 2, 2007
Messages
908
Location
USA
Corvette
1982 Black Fastback
I had the same problem on my 1982 when i bought it. Turns out that the valve was stuck open (just as 6880 Mike suggested).
I decided that it would be easier to just install a ball valve in the hose going to th heater core.
Downside: i have to pop my hood to turn the heater on/off
Upside: If my heater core springs a leak, I can shut off the flow of fluid.

If you want to keep your engine stock, then this is not your answer.
Personally, it doesn't bother me at all.

I know that a lot of other people have done this.

Good Luck.
 
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DaveMacGSP

Guest
Thanks

Mike and Mini Fridge,

Thanks for the advice. This appears to be a great forum for this type of thing.

Good riding!

Dave
'75 C3
 

bobfil

Well-known member
Joined
Jun 1, 2005
Messages
117
Location
roch.ny
Corvette
1972 convertible
heat from dash

How would you fix the valve to stop hot water from going into heater core? Bob
 

lone73

Well-known member
Joined
Sep 24, 2003
Messages
456
Location
Texas
Corvette
'73 4spd coupe, '04 6 speed coupe
This problem has plagued old C3'ers for ever and has been the topic of many discussions on various boards. If you find a real fix for it I'm all ears. I have tried taking the heater lines and short circuiting the heater core all together... same problem.

I personally think the hot air is coming in through the openings on either end of the wiper well and making its way into the system. Next time I get mine on the road (will be a while - its in bare glass) I want to try stuffing a wrag or piece of foam in them to block air. Then take it for an extended spin on a hot day and see how it does.
good luck.
.
.
.
 

MikeMc71

Well-known member
Joined
Apr 30, 2007
Messages
100
Location
Tucson, Arizona
Corvette
1970 Roadster, 1971 LT-1, 1971 Coupe

RMS73

Well-known member
Joined
Dec 16, 2001
Messages
64
Location
Chester, Va
Corvette
73 Dark Blue L-82
Check the weatherstripping that seals the hood to the firewall just in front of the wipers. If this weathertripping is not tight hot air from the engine compartment will come into the cowl area and then into the HVAC air inlet. I replaced this weatherstripping and I got cool air from the vent registers. I install a water cut off valve in my 73 - 73's did not come with one. I got one from a Ford Ranger that does just shut but allows the hot water to circulate without going into the heater core.
Roger
 
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DaveMacGSP

Guest
I had the same problem on my 1982 when i bought it. Turns out that the valve was stuck open (just as 6880 Mike suggested).
I decided that it would be easier to just install a ball valve in the hose going to th heater core.
Downside: i have to pop my hood to turn the heater on/off
Upside: If my heater core springs a leak, I can shut off the flow of fluid.

If you want to keep your engine stock, then this is not your answer.
Personally, it doesn't bother me at all.

I know that a lot of other people have done this.

Good Luck.

I replaced the valve that was there with a Ball Valve (from Ace Hardware). That made a huge difference. One other thing, the radiator fluid was real low, so adding fluid may have helped also.

I am attaching a picture of the original valve and the replacment.

Now on to the fixing the stereo that was not working. Someone took out the original and put in a Pioneer. If I can find an original I will try and replace it. The speakers at the kick plate were removed, so I am going to try and replace those.
 

Evolution1980

Well-known member
Administrator
Joined
Feb 25, 2002
Messages
4,302
Location
Cleveland, Ohio
Corvette
ZZ4, 700R4, Steeroids rack & pinion, VB&P Brakes
Now on to the fixing the stereo that was not working. Someone took out the original and put in a Pioneer. If I can find an original I will try and replace it.
Since you don't seemed concerned with originality, I wouldn't try to go back to an OEM-type radio. They were garbage and any of the remanufactured or post-type radios that you can still buy are overpriced garbage.
 

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