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Old 11-16-2005, 04:26 PM   #1
MASiefert
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Join Date: Jul 2004
Location: Dayton, Ohio
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Heater/Defroster Help

I am having issues with my heater/defroster on my 85 Burb. Maybe it's a common thing, maybe I have bigger issues, but anyway, here it is. All air comes out of the vents on the Dash. Some air will come out the defrost, but not enough to accomplish anything, when the defroster is turned on. The burb has air, and when I switch on the air the condenser seems to kick on. Is there something that get's stuck that I can check?
Thanx
MAS
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Old 11-16-2005, 09:21 PM   #2
JIMs70GMC
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Location: Chesapeake, Virginia
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Re: Heater/Defroster Help

Vaccum leak. When you move the selector from ac-vent-heat-defrost you should "hear" the vaccum change a door in the ductwork to redirect the air.
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1970 K25, 8' stepside bed 350/465/205 44 up front, 60 in the rear 4.10s rolling on 33" Dunlop MTs
1986 K5, 350/465/208 Dana 60/14 bolt from a cucv 36" Super Swampers TSL/SX
1983 K20 w/ CUCV axles, 350/700R4/208 sitting on 37" Goodyears
1986 M1031 6.2 diesel, TH400/NP205 locker in the rear and a LS in the front, all stock for now.....
1986 K30, 350/400/205 dana 60 and 14 bolt. I kept the drivetrain. Body/bad and chassis are gone.
1981 K30, 350/465/205 dana 60 and dually 14 bolt. Has a G80, and a flat bed. Going to replace the flat bed.

1985 K20, 350/400/208 10 bolt and SF 14 bolt. I wonder where I can find some 1 tons. Hmmmmm
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Old 11-17-2005, 01:38 PM   #3
toroflow
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Location: Anaheim, CA
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Re: Heater/Defroster Help

My '91 Sub does the dame danged thing!!! WHERE is there a vacuum leak??
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'60 GMC 3/4T 4x4
'60 GMC Suburban 4x4
'64 GMC Suburban 4x4
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Old 11-23-2005, 06:13 AM   #4
JIMs70GMC
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Re: Heater/Defroster Help

could be under the dash or in the engine compartment, you'll see the lines that go through the firewall near where all the windshield washer lines are.
__________________
1970 K25, 8' stepside bed 350/465/205 44 up front, 60 in the rear 4.10s rolling on 33" Dunlop MTs
1986 K5, 350/465/208 Dana 60/14 bolt from a cucv 36" Super Swampers TSL/SX
1983 K20 w/ CUCV axles, 350/700R4/208 sitting on 37" Goodyears
1986 M1031 6.2 diesel, TH400/NP205 locker in the rear and a LS in the front, all stock for now.....
1986 K30, 350/400/205 dana 60 and 14 bolt. I kept the drivetrain. Body/bad and chassis are gone.
1981 K30, 350/465/205 dana 60 and dually 14 bolt. Has a G80, and a flat bed. Going to replace the flat bed.

1985 K20, 350/400/208 10 bolt and SF 14 bolt. I wonder where I can find some 1 tons. Hmmmmm
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Old 12-01-2005, 09:38 PM   #5
blownz
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Location: Annapolis, MD
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Re: Heater/Defroster Help

It is the vacuum selector in the dash control. The selector is a small black plastic part that when you move the slide it changes the positions. GM still makes the part
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