heat, defrost, vent selector troubleshooting
Thread Starter
Race Director
Joined: Jul 2002
Posts: 13,858
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From: A 12/8 man in a 4/4 world
heat, defrost, vent selector troubleshooting
my heat, defrost, vent selector is stuck on heat. not the controlers but the deflector underneath. sounds like i have vacuum to the ac/heat control. looking for tips on trouble shooting. ive pulled the side panel off. everything looks ok. not sure what to do next. i would like to have defrost capabilites for this fall/winter
thanks in advance :chevy
thanks in advance :chevy
Burning Brakes
Joined: Jun 2002
Posts: 792
Likes: 2
From: Norcross GA
Re: heat, defrost, vent selector troubleshooting (Got79Fever)
I had the same problem. Here is a vacuum diagram
http://home.attbi.com/~jchadwick/climate-vacuum.pdf
that outlines the overall system. Are you getting vacuum from the switch to the other end of the black/blue vacuum hose that connects to the actuator on the left side of the air distributor behind the center console? If so, is it enough (I don't know what enough is). Can you "help" the unit change by hand?
Mine was getting about 8 - 10 pounds of vacuum but was not changing position. This gradually went away on its own, though I can hear the old springs under the dash creaking when it changes position.
Perhaps your problem is a combination of an old sticking actuator and low vacuum?
Bob
[Modified by Bobchad, 11:50 AM 8/21/2002]
http://home.attbi.com/~jchadwick/climate-vacuum.pdf
that outlines the overall system. Are you getting vacuum from the switch to the other end of the black/blue vacuum hose that connects to the actuator on the left side of the air distributor behind the center console? If so, is it enough (I don't know what enough is). Can you "help" the unit change by hand?
Mine was getting about 8 - 10 pounds of vacuum but was not changing position. This gradually went away on its own, though I can hear the old springs under the dash creaking when it changes position.
Perhaps your problem is a combination of an old sticking actuator and low vacuum?
Bob
[Modified by Bobchad, 11:50 AM 8/21/2002]
Advanced
Joined: Feb 1999
Posts: 84
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From: brownwood, tx
Re: heat, defrost, vent selector troubleshooting (Bobchad)
I had the same experience as Bobchad. I found that when I put the selector in the a/c max position & was getting air out of the center vents -- I could move the lever to the def. position & the air would get warm and start blowing out of the def. vent. After a period of time of doing this ever so often, I noticed that it started working as it should. Seveal times on this forum people have said that their a/c-heater wasn't working as it should, but after a while of using it - it began working right. I guess after all these years, grud & gunk builds up, lines get brittle, etc. Anyway, hope this works -- its always the "little" stuff that drives you crazy with these cars.
Thread Starter
Race Director
Joined: Jul 2002
Posts: 13,858
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From: A 12/8 man in a 4/4 world
Re: heat, defrost, vent selector troubleshooting (Got79Fever)
bobchad.
thanks for the diagram. sure lot easier to read than the assembly manual.
ready to tackle problem. i think the deflector is hung up. wasnt sure how much pressure to use when moving it buy hand. plan on checking all the vacuum point. my temp selector was broken on HOT! but bypassed the heater core. now the temp selector is fixed. ready to tackle where i want the heat. even if it wont move. id rather have defrost over heat at my feet. (like these cars need to have hot air blowing on your feet!)
thanks for the diagram. sure lot easier to read than the assembly manual.
ready to tackle problem. i think the deflector is hung up. wasnt sure how much pressure to use when moving it buy hand. plan on checking all the vacuum point. my temp selector was broken on HOT! but bypassed the heater core. now the temp selector is fixed. ready to tackle where i want the heat. even if it wont move. id rather have defrost over heat at my feet. (like these cars need to have hot air blowing on your feet!)
Burning Brakes
Joined: Jun 2002
Posts: 792
Likes: 2
From: Norcross GA
Re: heat, defrost, vent selector troubleshooting (Got79Fever)
Good luck Mike. I'm going to be taking the center console out this Winter to insulate the cabin. When I do I'm thinking of replacing the heater/a/c control to see if this has any impact on consistency. I think it is about $80 at http://www.tld-corvette.com. You might want to consider this as well.
Thank Vmrod at the Corvette Action Center for the diagram. He did an excellent job with this one, as well as one on the cruise control that have been very helpful to me.
Bob
[Modified by Bobchad, 7:44 AM 8/22/2002]
Thank Vmrod at the Corvette Action Center for the diagram. He did an excellent job with this one, as well as one on the cruise control that have been very helpful to me.
Bob
[Modified by Bobchad, 7:44 AM 8/22/2002]
Melting Slicks
Joined: Oct 2000
Posts: 2,268
Likes: 0
From: Roanoke Virginia
Re: heat, defrost, vent selector troubleshooting (Bobchad)
You said your temp control was stuck on heat. how did you fix it? Reason I'm asking, the temp and air outlet controls are held together with a plastic rivit, between which is the rubber "rat maze" that dictates where vacuum goes. the plastic rivit is easily broken after 25 years, and the rat maze may either have shifted or is loosing too much vacuum because the contrjols have separated. I would look into that.
Jeff
Jeff
Thread Starter
Race Director
Joined: Jul 2002
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From: A 12/8 man in a 4/4 world
Re: heat, defrost, vent selector troubleshooting (thejaf)
the plastic rivet was broken at the selector switch. i 'bubba'd" it with a wire wrap. thru the whole and around the mount. moves ok. havent hooked hoses up to heater core yet so i dont know how much heat it will keep out. :smash:
Melting Slicks
Joined: Oct 2000
Posts: 2,268
Likes: 0
From: Roanoke Virginia
Re: heat, defrost, vent selector troubleshooting (Got79Fever)
I Bubba'd the one in my 1978 also, however I found that the late-model GM plastic interior rivets worked GREAT as a replacement for that broken rivet. Just snapped in place nicely.
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