Heat/AC problem, won't change to different outlets - The 1947 - Present Chevrolet & GMC Truck Message Board Network

glock35ipsc · 09-17-2010, 10:10 AM

We have my brother's "new" 2000 running great after replacing the fuel pump and filter, now we have a heat/AC problem. Now matter what position the selector is in (dash, defrost, floor, bi-level, etc) we are not getting air coming out of anywhere. There is a little that can be felt through the floor, but the bottom line is the doors are not moving. The blower will run through all the speeds just fine, but we just can't change the outlet position.

Are these vacuum controlled or electric? I can only guess electric since I can't find a vacuum hose going through the firewall anywhere under the hood.

A little background on this truck..... when the fuel pump went out, the P/O just towed it home and parked it, and it sat for about 1 year. I don't suspect that mice got in the interior, though I guess it's still a possibility. But there was no evidence of mice inside the truck, and there is no smell (you know that smell I'm talking about!

) coming from any of the vents when the fan is on high, nor is there any "mouse house" stuff coming out of any of the vents.

Anyone else had this problem, or know where to start?

Thanks in advance.

PT'S 70 CST · 09-20-2010, 09:30 AM

I know this sounds kinda crazy but these trucks, burbs and tahoe's had a bad problem with the temp control switch panel. Although this does not sound like it may be your problem the switch could be stuck in a floor selection mode or something. I may have a spare if yours looks like this.

bulldoggraphics · 10-04-2010, 07:33 PM

I have had the same problem there is a control servo just above the brake pedal if you notice the air will blow out of the dash then when the car primes up and the fuel pump relay turns off the air blows through the defrosters, that servo controls these vents you can pull the wire to make it stay in the dash until you have time (30min)or the money ($50) to buy the control head unit, but that will fix your a/c/ problem
Hope this helps

glock35ipsc · 10-05-2010, 09:40 AM

Thanks guys!

bullydog - By saying "control head unit", are you referring to the dash switch cluster like PT'S 70 CST posted?

09-17-2010, 10:10 AM	#1
glock35ipsc Next project: 1970 K10 Join Date: Feb 2004 Location: Fort Collins, Colo 80524 Posts: 6,684	Heat/AC problem, won't change to different outlets We have my brother's "new" 2000 running great after replacing the fuel pump and filter, now we have a heat/AC problem. Now matter what position the selector is in (dash, defrost, floor, bi-level, etc) we are not getting air coming out of anywhere. There is a little that can be felt through the floor, but the bottom line is the doors are not moving. The blower will run through all the speeds just fine, but we just can't change the outlet position. Are these vacuum controlled or electric? I can only guess electric since I can't find a vacuum hose going through the firewall anywhere under the hood. A little background on this truck..... when the fuel pump went out, the P/O just towed it home and parked it, and it sat for about 1 year. I don't suspect that mice got in the interior, though I guess it's still a possibility. But there was no evidence of mice inside the truck, and there is no smell (you know that smell I'm talking about! ) coming from any of the vents when the fan is on high, nor is there any "mouse house" stuff coming out of any of the vents. Anyone else had this problem, or know where to start? Thanks in advance. __________________ *Bob* 1970 Chevy K10 LWB "Goldie" 350/TH350 *next project!!* 1981 Chevy C10 LWB 355/TH350 - My son's truck LS SWAP FORUM! Tons of LS swap info here! PLEASE CLICK HERE TO SUPPORT THE GREATEST BOARD ON THE NET! CLICK HERE FOR THE FAQ INDEX by KRUE

09-20-2010, 09:30 AM	#2
PT'S 70 CST "GO DAWGS" Join Date: Oct 2003 Location: Batesburg, SC. 29006 Posts: 5,410	Re: Heat/AC problem, won't change to different outlets I know this sounds kinda crazy but these trucks, burbs and tahoe's had a bad problem with the temp control switch panel. Although this does not sound like it may be your problem the switch could be stuck in a floor selection mode or something. I may have a spare if yours looks like this. Attached Images __________________ 70 CST SWB 70 NOVA 93 Indy 500 Pace Truck (SOLD) 94 SILVERADO SWB 5/7 drop 2000 Silverado swb 2005 Nissan Altima 3.5 (Surprisingly very fast) 2004 GMC Yukon XL Denali BATESBURG, SC. 29006 29006 Some of my restorations http://www.snapfish.com/snapfish/thu...NAME=snapfish/ Restored Tach tins 8 cyl - 6 cyl http://67-72chevytrucks.com/vboard/s...d.php?t=518185 Contact info(Not my paypal address) DAWGSFAN227@YAHOO.COM God Bless Our Troops

10-04-2010, 07:33 PM	#3
bulldoggraphics Registered User Join Date: Sep 2010 Location: Tucson, Arizona Posts: 30	Re: Heat/AC problem, won't change to different outlets I have had the same problem there is a control servo just above the brake pedal if you notice the air will blow out of the dash then when the car primes up and the fuel pump relay turns off the air blows through the defrosters, that servo controls these vents you can pull the wire to make it stay in the dash until you have time (30min)or the money ($50) to buy the control head unit, but that will fix your a/c/ problem Hope this helps

10-05-2010, 09:40 AM	#4
glock35ipsc Next project: 1970 K10 Join Date: Feb 2004 Location: Fort Collins, Colo 80524 Posts: 6,684	Re: Heat/AC problem, won't change to different outlets Thanks guys! bullydog - By saying "control head unit", are you referring to the dash switch cluster like PT'S 70 CST posted? __________________ *Bob* 1970 Chevy K10 LWB "Goldie" 350/TH350 *next project!!* 1981 Chevy C10 LWB 355/TH350 - My son's truck LS SWAP FORUM! Tons of LS swap info here! PLEASE CLICK HERE TO SUPPORT THE GREATEST BOARD ON THE NET! CLICK HERE FOR THE FAQ INDEX by KRUE



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