heater problems
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Originally Posted by markdtn
The vacuum valve in the HVAC control. They come apart causing the condition you mention. Also if you have no vacuum to the inside of the car same thing.
What is the HVAC control and where is it located on the car?
Also in the event there are no vacum lines coming into my 1980 ("Buba" has worked on the car in years past) where should the vacum source be and what path does it take to get to the HVAC control?
greatful for the help
Boby06
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theres a acuator diaphram that open/closes for heat-then to defrost- get on the drivers side floor and look up and to the left and you'll see the acuator- unplug the vaccume line plug in a spare and apply vaccume to see if it opens and closes.,, if it does your not getting vaccume to the acuator,,then you have to trace it back to the vaccume dial on the heater control switch,,,i color coated a vaccume diagram from the assembly manual the same colors as the vaccume lines- and went thru the entire system,,,, my problem was bubba pinched off the source vaccume line when he installed the cassette player,,shutting down the entire vacume heat/defrost--a/c system- pretty e/z if you take the time to trace it all out-need that diagram thou
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thanks carl a
Thinks for the loction and starting point for this weekend project. I am begining to get the pictue on how this system works and Buba did put a radio in so who knows I may have the same problem as you.
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somebody here's can probably scan and e mail you the vaccume diagram if you dont have it- mine's outta the 1973 assembly manual-----those vaccume port distributer valves were used on all sorts of gm heater/vaccume systems not just vettes- i ran a vaccume line to it from the manifold and every thing started workin ,,,so i knew the thing(vaccume port distributer wasnt gettin suction- then i saw the pinch behind the radio bubba left for me- what a guy!- yours should work the same as mine as far as- when you turn the a/c to max air 2 things happen-#1the flapper closes in the wiper well so fresh air cannot get in(but it will, poor design)- #2 it openes the flapper in the kick panel so the blower is now pullin air from the **** pit-re-cicle mode- the other diaphram is the one your lookin for that controls heat and defrost-its so e/z once you get your hands in there you'll see what i mean- im a electrican by trade so i just get off on making drawings as builts or color coding different systems cuz its e/z er to take it all in once you can arrange it in your head- im not sure if they used the same system in 1980 ,, i only worked on a 77 and my 73 so kinda liminited in different years
Last edited by carl a; Dec 2, 2004 at 03:35 PM.
Burning Brakes
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From: Norcross GA
Here's the vacuum diagram for a 77.
http://home.comcast.net/~chadwick.ro...ate-vacuum.pdf
The source line comes off the manifold and is near the power brake booster. There is a T with two large legs and a small leg. The smal leg is the source for the heater system. It goes into the car behind the distributor.
http://home.comcast.net/~chadwick.ro...ate-vacuum.pdf
The source line comes off the manifold and is near the power brake booster. There is a T with two large legs and a small leg. The smal leg is the source for the heater system. It goes into the car behind the distributor.
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Originally Posted by carl a
somebody here's can probably scan and e mail you the vaccume diagram if you dont have it- mine's outta the 1973 assembly manual-----those vaccume port distributer valves were used on all sorts of gm heater/vaccume systems not just vettes- i ran a vaccume line to it from the manifold and every thing started workin ,,,so i knew the thing(vaccume port distributer wasnt gettin suction- then i saw the pinch behind the radio bubba left for me- what a guy!- yours should work the same as mine as far as- when you turn the a/c to max air 2 things happen-#1the flapper closes in the wiper well so fresh air cannot get in(but it will, poor design)- #2 it openes the flapper in the kick panel so the blower is now pullin air from the **** pit-re-cicle mode- the other diaphram is the one your lookin for that controls heat and defrost-its so e/z once you get your hands in there you'll see what i mean- im a electrican by trade so i just get off on making drawings as builts or color coding different systems cuz its e/z er to take it all in once you can arrange it in your head- im not sure if they used the same system in 1980 ,, i only worked on a 77 and my 73 so kinda liminited in different years
Bobby06
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thanks
Originally Posted by Bobchad
Here's the vacuum diagram for a 77.
http://home.comcast.net/~chadwick.ro...ate-vacuum.pdf
The source line comes off the manifold and is near the power brake booster. There is a T with two large legs and a small leg. The smal leg is the source for the heater system. It goes into the car behind the distributor.
http://home.comcast.net/~chadwick.ro...ate-vacuum.pdf
The source line comes off the manifold and is near the power brake booster. There is a T with two large legs and a small leg. The smal leg is the source for the heater system. It goes into the car behind the distributor.
Bobby06
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also if you look at the vaccume valve distributor ( or whatever you call that rotary thing that sends vaccume to the different diaphrams) i believe the source vaccume line to that switch was solid black- the loads have stripes on them ,,green red ect- (im going from memory here)sorry i forgot i had that chadwicks stored in my favorates!- take that puppy off and see if its suckin if not there you go- if it is gotta keep on lookin -disconnect one at a time and apply a known vaccume source- i put a vaccume line over the drivers fender and started hittin the loads--- i also made a jumper outa a line splice(little piece of hard plastic tube that you would splice vaccume lines tog--if there all workin with the vaccume line you throw over the fender- that switch might be the trouble-there in the catalogs
Last edited by carl a; Dec 2, 2004 at 07:05 PM.
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From: CORVETTE 77 385 C.I. TEXAS
I wrote up something for you guys & have posted it several times:
On at least later C3 the problem is that heater is the default position (no vac. or vac. leak) due to being designed in the north. Vent should be default. Very safe bet the problem is 1 OR 2:
1) The vac. line from engine is damaged from heat - a small plastic tube that goes in below the hood theft switch into wiper valley. Replacing most of engine side w/ hose will fix. OR
2) The vac. switch itself is not switching due to vac. leak as the usually plastic rivet is not holding the 2 main switch parts together well. Besides replacing, it is also possible to tighten this &/or lube w/ a thin layer of white lithium grease or vasoline to fix.
3) If you have a heater, the small hose to heater hose valve underhood probably also needs replacing. Block w/o heater.
PS The design problem comment is not intended to be offensive to any of our northern friends.
On at least later C3 the problem is that heater is the default position (no vac. or vac. leak) due to being designed in the north. Vent should be default. Very safe bet the problem is 1 OR 2:
1) The vac. line from engine is damaged from heat - a small plastic tube that goes in below the hood theft switch into wiper valley. Replacing most of engine side w/ hose will fix. OR
2) The vac. switch itself is not switching due to vac. leak as the usually plastic rivet is not holding the 2 main switch parts together well. Besides replacing, it is also possible to tighten this &/or lube w/ a thin layer of white lithium grease or vasoline to fix.
3) If you have a heater, the small hose to heater hose valve underhood probably also needs replacing. Block w/o heater.
PS The design problem comment is not intended to be offensive to any of our northern friends.
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From: Minot ND
The vacuum hose runs past the distributer cover, and I accidently pinched the hose in two places. It did the exact same thing your experiencing. No worries easy fix.........just takes time to track down the collapsed or broken line. Good luck.
Ron
Ron
