C3 General General C3 Corvette Discussion not covered in Tech
Sponsored by:
Sponsored by:

Upper defroster not working

Thread Tools
 
Search this Thread
 
Old 10-11-2009, 11:34 AM
  #1  
RedZR
Burning Brakes
Thread Starter
 
RedZR's Avatar
 
Member Since: Aug 2000
Location: Morgantown,WV USA
Posts: 952
Likes: 0
Received 0 Likes on 0 Posts

Default Upper defroster not working

My 78's blower & temp control is working just fine (good news) but it keeps blowing toward the floor regardless of what selection I choose.

I have been doing quite a bit of research on the subject from the archives on the forum and have a couple of questions.

I removed the side panel (of the console) and on the drivers side found the vacuum line that attaches what I think is the defroster valve. I replaced the vacuum source with a hose and drew vacuum from my miti-vac and the air flow shifted to the defroster. Thus, it appears that the door is working ok.

Based on what I have found thus far, does anyone have any suggested area I can look at to solve this problem?
I did locate the vacuum source from the engine (a small black hose on the drivers side of the car and cranked on it with the miti-vac and it would not hold vacuum. I do not know if this is relevent or not.

Any help is appreciated!
Dan
Old 10-11-2009, 12:39 PM
  #2  
7T1vette
Team Owner
 
7T1vette's Avatar
 
Member Since: Jan 2006
Location: Crossville TN
Posts: 36,600
Received 2,713 Likes on 2,271 Posts

Default

Putting your vac hand-pump on the supply line would not do much as you would have to pump long enough to draw-down the vacuum reservoir tank in the left front fender. Now, if that pump has a gauge and you were to leave it connected to that supply line and start the car, you could find out how much vacuum you have at that point (once it stabilized). If you have at least 12" Hg, the A/C vacuum system should work unless there is another leak somewhere. The most likely place for such a leak is at the distribution manifold on the left side of the heater/A/C control in your trans console.



Quick Reply: Upper defroster not working



All times are GMT -4. The time now is 02:40 AM.