Defroster/Heater Help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Paul Clark · 09-22-2002, 09:12 PM

72 C10 w/AC
New heater and AC hoses under the dash.
Have plenty of heat coming out of the floor vent. Not much coming out of the defrosters. More from the driver side than from the passenger side.
Need to fix this, but not sure how.
Gotta have good defrosters to make up for those little wipers.
Thanks

mt Al · 09-22-2002, 09:39 PM

Check the diverter boxes and cable connections. The one you can see to the right of the heater outlet diverts air to either the heater outlet or to the defrosters. Move the slide back and forth and make sure that its moving the diverter flap axis. If it isn't moving, your cable end may have disconnected from the post on the back of the slide. If it IS moving and the air is still coming out of the floor, its very possible that the axis and flap (inside the box) have had an unfortunate separation. Its very possible to have the axle moving and the flap just sitting there. The connection leaves a lot to be disired. You can take the box off and move the axis by hand and see if the flap is moving.

That's my 2 cents. Have fun.

tom hand · 09-22-2002, 09:57 PM

mt Al has the answer. More than likely the flap has come loose from the rod that operates it. The good news is it can be fixed without $ just a lot of work. If the cable is hooked up and appears to operate, remove the diverter box. If the flap is loose,[ which would be my bet] you have two optons. You can buy some epoxy and glue it up. It will work but plan to do it again in two or three years. Option two is a little more work but is a permanet fix. Cut a piece of sheetmetal a little smaller than the flap. Drill a few holes in the middle to line up with the shaft that operates the flap. Use a mig welder to tack weld the sheetmetal to the shaft, and screw it to the flap. The main thing is to have the flap in the same position it was originaly. Confused yet? Good Luck

09-22-2002, 09:12 PM	#1
Paul Clark Registered User Join Date: Apr 2002 Location: Center Point, IA Posts: 502	Defroster/Heater Help 72 C10 w/AC New heater and AC hoses under the dash. Have plenty of heat coming out of the floor vent. Not much coming out of the defrosters. More from the driver side than from the passenger side. Need to fix this, but not sure how. Gotta have good defrosters to make up for those little wipers. Thanks

09-22-2002, 09:39 PM	#2
mt Al Registered User Join Date: Aug 2001 Location: Bozeman, Montana Posts: 243	Check the diverter boxes and cable connections. The one you can see to the right of the heater outlet diverts air to either the heater outlet or to the defrosters. Move the slide back and forth and make sure that its moving the diverter flap axis. If it isn't moving, your cable end may have disconnected from the post on the back of the slide. If it IS moving and the air is still coming out of the floor, its very possible that the axis and flap (inside the box) have had an unfortunate separation. Its very possible to have the axle moving and the flap just sitting there. The connection leaves a lot to be disired. You can take the box off and move the axis by hand and see if the flap is moving. That's my 2 cents. Have fun. __________________ '72 GMC 1/2T 4x4 1500 Super Custom pickup (current) past rides were: '70 Chev 2wd farm truck '71 GMC 2wd 1/2T 402 nice! '72 Chev 2wd 1/2T 396 '72 GMC 3/4T 4x4 2500 Super Custom suburban. Bozeman, Montana

09-22-2002, 09:57 PM	#3
tom hand CCRider Join Date: Feb 2000 Location: Olive Branch,MS,USA Posts: 2,232	mt Al has the answer. More than likely the flap has come loose from the rod that operates it. The good news is it can be fixed without $ just a lot of work. If the cable is hooked up and appears to operate, remove the diverter box. If the flap is loose,[ which would be my bet] you have two optons. You can buy some epoxy and glue it up. It will work but plan to do it again in two or three years. Option two is a little more work but is a permanet fix. Cut a piece of sheetmetal a little smaller than the flap. Drill a few holes in the middle to line up with the shaft that operates the flap. Use a mig welder to tack weld the sheetmetal to the shaft, and screw it to the flap. The main thing is to have the flap in the same position it was originaly. Confused yet? Good Luck __________________ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS



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