Need Help with Heater/Defrost - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Blue85 · 12-06-2004, 11:11 AM

On my 70 GMC (with A/C) the defrost isnt working, there is warm air coming from the vents but the windshield won't unthaw, any ideas?

JimKshortstep4x4 · 12-06-2004, 12:02 PM

It is probably your diverter box. The doors come loose from the shaft that moves the door and the shaft moves but the door doesn't. That would be the first place to check. (The diveter box is next to the heater box).

Jim

jhow66 · 12-06-2004, 01:11 PM

Maybe your defrost hoses are off the vents.

12-06-2004, 11:11 AM	#1
Blue85 Oilfield Trash Join Date: Sep 2003 Location: Raymore, Sk, Canada, Earth Posts: 3,171	Need Help with Heater/Defrost On my 70 GMC (with A/C) the defrost isnt working, there is warm air coming from the vents but the windshield won't unthaw, any ideas? __________________ 14 Dodge 3500 Mega Cab 08 Dodge 3500 Mega Cab 87 Chev 3+3 4x4 80 GMC K10 High Sierra bone stock 70 Chevelle 350SS long term project 68 GMC 3ton Grain Truck/Garbage wagon 50 Pontiac 2 Door Coupe Project "I've got a shotgun rifle and a 4 wheel drive and a country boy can survive" Hank Jr.

12-06-2004, 01:11 PM	#3
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	Maybe your defrost hoses are off the vents. __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

12-06-2004, 12:02 PM	#2
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	It is probably your diverter box. The doors come loose from the shaft that moves the door and the shaft moves but the door doesn't. That would be the first place to check. (The diveter box is next to the heater box). Jim



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