77 Heat & Defrost Problem
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 828
Likes: 2
77 Heat & Defrost Problem
Hi All,
I changed the rear vacuum switch on the control and some of the hoses. I still get no air switching to the defrost or heat. Is there a diaghragm or chapter anywhere on this.
DUB, told me to remove the center panel and pocket panel and go from there, then look, but I was hoping that there was a schematic somewhere.
The A/C did work in the summer and the fan switch works.
Thanks
Jack
I changed the rear vacuum switch on the control and some of the hoses. I still get no air switching to the defrost or heat. Is there a diaghragm or chapter anywhere on this.
DUB, told me to remove the center panel and pocket panel and go from there, then look, but I was hoping that there was a schematic somewhere.
The A/C did work in the summer and the fan switch works.
Thanks
Jack
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
Have you checked the source. The vac. line from engine may be damaged from heat - a small plastic tube that goes in below the hood alarm switch into wiper valley. Replacing most of engine side w/ hose will normally fix if damaged.
If you have a heater, the small vac. tube to heater hose valve underhood may be damaged from heat & need replacing. Block w/o heater.
Try pressing the 2 halves of the switch together.
Check tube to vent vac. motor & apply vacuum directly.
SEE ALSO
http://willcoxcorvette.com/images/77...ol%20chart.jpg
If you have a heater, the small vac. tube to heater hose valve underhood may be damaged from heat & need replacing. Block w/o heater.
Try pressing the 2 halves of the switch together.
Check tube to vent vac. motor & apply vacuum directly.
SEE ALSO
http://willcoxcorvette.com/images/77...ol%20chart.jpg
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 828
Likes: 2
Have you checked the source. The vac. line from engine may be damaged from heat - a small plastic tube that goes in below the hood alarm switch into wiper valley. Replacing most of engine side w/ hose will normally fix if damaged.
If you have a heater, the small vac. tube to heater hose valve underhood may be damaged from heat & need replacing. Block w/o heater.
Try pressing the 2 halves of the switch together.
Check tube to vent vac. motor & apply vacuum directly.
SEE ALSO
http://willcoxcorvette.com/images/77...ol%20chart.jpg
If you have a heater, the small vac. tube to heater hose valve underhood may be damaged from heat & need replacing. Block w/o heater.
Try pressing the 2 halves of the switch together.
Check tube to vent vac. motor & apply vacuum directly.
SEE ALSO
http://willcoxcorvette.com/images/77...ol%20chart.jpg
Hi Ganey,
How are you holding up in this winter?
My main black line is fine, I actually was able to put my tongue to the inside switch side of it and I felt the suction.
The switch doesn't go to defrost, only blows out of the lower A/C area.
The lower (Blue - Red) lever moves and the inner cable does move. There is no heat from moving it.
Are there any chapters in any manuals that you know of that breaks this system down?
Thanks
Jack
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
Jack
Follow that Blue-Red lever cable, it is probably not moving the "vent or door". I have seen that on other GMs.
If broken the "vent or door" can be moved manually into position.
No, not that I have noticed (or really looked).
Follow that Blue-Red lever cable, it is probably not moving the "vent or door". I have seen that on other GMs.
If broken the "vent or door" can be moved manually into position.
No, not that I have noticed (or really looked).
