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Defroster not working

Doug57

Member
Joined
Aug 20, 2002
Messages
23
Defroster not working,air blows to the floor, but not to the windshield.Need it for state inspection.Any help would be appreciated.Thanks
 

68sunlitgold

Well-known member
Joined
Aug 20, 2002
Messages
1,357
Doug57,
The problem seems to be with the Plenum Chamber. The plenum chamber switches the heat from the floor to the window defrosters. There could be 2 possible problems:
1) the plenum is made from a stiff cardboard and over time it will detiorate, they make plastic reproductions. If it has fallen apart, there is no way to redirect the air to the defrosters. You will need to replace it.
2) the plenum cable may have come loose.
The plenum is located under the dash next to the heater core case, it is directly under the radio. On the left side of the plenum is a crank arm which should have a cable attached to it. This lever should be moved to the left (clock-wise) which will take the heat and direct it to the defrost. This should send the heat up to the windows.
Doug
 
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Doug57

Member
Joined
Aug 20, 2002
Messages
23
Hi Doug, Thanks for the reply. I did find what might be the Plenum Chamber. Is it round, and about 2 inches in length? When I cranked the lever it did bring the air from the floor to the center of the dash,right above the radio.I turned it as far as I could, but it didn't make it to the windshield.I'll take any other suggestions. I took out the temp, and fan controls from dash, found 4 vaccum lines,and 1 cable at the top of the control. Should there be another cable at the bottom of the control?Thanks again.
 

68sunlitgold

Well-known member
Joined
Aug 20, 2002
Messages
1,357
Doug57,
I did not know your car had indash A/C, that is a totally different system. I am assuming you have A/C because you said you had vacuum hoses.
Ok, lets start over. The round thing you found is the blower assemble, and the lever you pulled that made the air go to the dash is a good start, keep that lever in that position. Now look above the blower for the A/C plenum chamber, there is a lever on it also, move it and it will change the air from the dash to the defroster.
I have attached a picture of the blower and the plenum chamber, the plenum is the part to the right with the yellow words on it, and the lever I am speaking of is circled. I hope this helps
Doug
 

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Doug57

Member
Joined
Aug 20, 2002
Messages
23
Doug, Thanks for the response. I do have A/C. On my car I only see the one chamber on the drivers side, but there's two on the passengers side.I was able to hold down two of the three chambers, but I still couldn't get the air to the windshield. I alternated holding the one on the drivers side, and the two on the passenger side. I'll try holding the levers on all three when I get someone to lend me a hand.I'm leaving today for business, won't be able to try again till next weekend. Thanks.
 

68sunlitgold

Well-known member
Joined
Aug 20, 2002
Messages
1,357
Doug57,
I guess I did not address what the fix for the problem could be, just how to make it work. Because all the crank levers work on vacuum, that is where the problem will most likely be. It could be:
- the vacuum lines in the engine
- the ones under the dash
- the vacuum motors that open/close dampers (these are what are attached to the cranks, you can see 2 in the pictures above)
- the vacuum tank in the engine bay may have a leak
- a vacuum line may be pinched
As you can see, the only way to track down the problem is to have a vacuum tester and go through all the lines.
Doug
 
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Doug57

Member
Joined
Aug 20, 2002
Messages
23
:)Doug,thanks for all the help. You were a big help. Car passed inspection.
 

68sunlitgold

Well-known member
Joined
Aug 20, 2002
Messages
1,357
Doug57,
Glad to be some help. Did you find and fix the problem or did you just get it to work for the inspection?
Doug
 
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