Defroster woes - The 1947 - Present Chevrolet & GMC Truck Message Board Network

shuttermutt · 12-14-2003, 07:43 PM

Well, the new 350 is running strong. A bit more cam than I would have picked myself for a street engine, but I can live with it. Sure does like that premium gas!

But, with the good comes the bad. I recently re-cored my heater core and the heat works awesome. The only problem is that no matter where I move the top lever, I only get heat from the center A/C vent (yes, it has factory A/C). I can see the cable moving the lever on the front of the Mysterious Black Box directly below the controls, but it doesn't seem to change anything.

Anybody here have an idea before I have to walk out in the 15 degree weather and tear everything apart? Frankly, I'd rather have a good defroster than a blast of hot air from the center vent. Seeing comes first, ya know.

**old Rusty C10** · 12-14-2003, 07:46 PM

the cable sounds like its not moving the door to switch between the vent to defroster

PanelDeland · 12-14-2003, 07:50 PM

Check to be sure the defrost hoses are routed correctly.Could be the defrost is hooked to that center vent.

*rage'nrat638* · 12-14-2003, 07:51 PM

THE SECOND LEVER MOVE'S THE OTHER FLIPPER ON THE PASSENGER SIDE...AND HAS THE VACUUM SWITCH HOOKED UP TO IT...
VAC SWITCH HAS 3 PORTS #1 IS VAC OF THE ENGINE
#2 GOES TO THE LITTLE DOOR ON THE PASSENGER SIDE
#3 GOES TO THE VAC SWITCH UNDER THE HOOD OVER THE A/C BOX

OldSkool71 · 12-14-2003, 07:55 PM

I am having the same problem. A defroster would be nice right about now. I welcome all input as well.

Longhorn Man · 12-14-2003, 07:57 PM

Instead of tearing it all apart in the driveway when it is cold, follow your A/C vent hoses, and then unplug the large plack hose from them. Then, find your defroster hoses and plug them into the ports that are blowing hot air. you may need some duct tape too becouse the hoses will tear if original.
This will gewt you to work in the morning with a de-fogged windshield. You'll need to rip apart the magic black box come spring time allong with replacing the hoses.

*rage'nrat638* · 12-14-2003, 07:57 PM

IF YOU GUY'S WANT I WILL GO TAKE A PICTURE OF THE BLUE PRINT IN MY MANUAL

shuttermutt · 12-14-2003, 08:03 PM

Quote:

Originally posted by rage'nrat638
IF YOU GUY'S WANT I WILL GO TAKE A PICTURE OF THE BLUE PRINT IN MY MANUAL

Oh, man... that'd be SWEET! Longhorn Man does have a rather pragmatic approach, though.

Duffy · 12-14-2003, 08:25 PM

I had this problem with my '71 Custom Camper. It had factory AC and I couldn't get any air out of the defroster vents. I took everything apart under the dash and found the air diverter door inside the plenum was broken. No matter which way the lever was moved, the diverter door stayed in the heat only position. I was able to fix the door by wrapping a piece of sheet metal around it to hold the two pieces firmly together.

Hope this helps....

Duff

*rage'nrat638* · 12-14-2003, 08:28 PM

hose route's

*rage'nrat638* · 12-14-2003, 08:29 PM

vacuum hoses

*rage'nrat638* · 12-14-2003, 08:31 PM

outside a/c box hose's

shuttermutt · 12-14-2003, 08:43 PM

Most outstanding, Rage'nRat638! Your efforts are VERY appreciated! This will help a lot!

OldSkool71 · 12-14-2003, 09:17 PM

Are those pics from the factory service manual? Damn I have to have one of those if so.

*rage'nrat638* · 12-14-2003, 09:55 PM

BEST BOOK I HAVE BOUGHT SO FAR..................

cwilli84 · 12-14-2003, 10:07 PM

I've got a 70 copy not any difference I noticed from a 69. Somebody wanna buy it. $20 +shipping

krue · 12-14-2003, 11:36 PM

Is there any difference between Chevy and GMC manuals?

cwilli84 · 12-14-2003, 11:43 PM

Not sure if anything significatly different but I have seen they have a differnet cover on them.

12-14-2003, 07:55 PM	#5
OldSkool71 C/10 CLUB MEMBER Join Date: Jul 2003 Location: Lakewood, CA Posts: 993	I am having the same problem. A defroster would be nice right about now. I welcome all input as well. __________________ -Ron-

12-14-2003, 08:25 PM	#9
Duffy Registered User Join Date: Jan 2001 Location: Billings, MT Posts: 121	I had this problem with my '71 Custom Camper. It had factory AC and I couldn't get any air out of the defroster vents. I took everything apart under the dash and found the air diverter door inside the plenum was broken. No matter which way the lever was moved, the diverter door stayed in the heat only position. I was able to fix the door by wrapping a piece of sheet metal around it to hold the two pieces firmly together. Hope this helps.... Duff __________________ '72 GMC Sierra Grande Custom Camper Last edited by Duffy; 12-14-2003 at 10:35 PM.

12-14-2003, 08:28 PM	#10
rage'nrat638 Account Suspended Join Date: Mar 2003 Location: THE FALL GUY CHICAGO IL Posts: 5,883	hose route's Last edited by rage'nrat638; 07-12-2007 at 07:09 AM.

12-14-2003, 08:29 PM	#11
rage'nrat638 Account Suspended Join Date: Mar 2003 Location: THE FALL GUY CHICAGO IL Posts: 5,883	vacuum hoses Last edited by rage'nrat638; 07-12-2007 at 07:09 AM.

12-14-2003, 08:31 PM	#12
rage'nrat638 Account Suspended Join Date: Mar 2003 Location: THE FALL GUY CHICAGO IL Posts: 5,883	outside a/c box hose's Last edited by rage'nrat638; 07-12-2007 at 07:09 AM.

12-14-2003, 07:43 PM	#1
shuttermutt Don't say "Oops!", Doctor Join Date: Nov 2003 Location: Houston, TX Posts: 677	Defroster woes Well, the new 350 is running strong. A bit more cam than I would have picked myself for a street engine, but I can live with it. Sure does like that premium gas! But, with the good comes the bad. I recently re-cored my heater core and the heat works awesome. The only problem is that no matter where I move the top lever, I only get heat from the center A/C vent (yes, it has factory A/C). I can see the cable moving the lever on the front of the Mysterious Black Box directly below the controls, but it doesn't seem to change anything. Anybody here have an idea before I have to walk out in the 15 degree weather and tear everything apart? Frankly, I'd rather have a good defroster than a blast of hot air from the center vent. Seeing comes first, ya know. __________________ 'Mutt 1968 CST LWB: R.I.P. 1967 Chevelle: TPI 454 beast 1967 C10 SWB: Claimed when Bumpster didn't put it on his list

12-14-2003, 07:46 PM	#2
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,303	the cable sounds like its not moving the door to switch between the vent to defroster __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!!

12-14-2003, 07:50 PM	#3
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,993	Check to be sure the defrost hoses are routed correctly.Could be the defrost is hooked to that center vent. __________________ The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil"

12-14-2003, 07:51 PM	#4
rage'nrat638 Account Suspended Join Date: Mar 2003 Location: THE FALL GUY CHICAGO IL Posts: 5,883	THE SECOND LEVER MOVE'S THE OTHER FLIPPER ON THE PASSENGER SIDE...AND HAS THE VACUUM SWITCH HOOKED UP TO IT... VAC SWITCH HAS 3 PORTS #1 IS VAC OF THE ENGINE #2 GOES TO THE LITTLE DOOR ON THE PASSENGER SIDE #3 GOES TO THE VAC SWITCH UNDER THE HOOD OVER THE A/C BOX

12-14-2003, 07:57 PM	#6
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Instead of tearing it all apart in the driveway when it is cold, follow your A/C vent hoses, and then unplug the large plack hose from them. Then, find your defroster hoses and plug them into the ports that are blowing hot air. you may need some duct tape too becouse the hoses will tear if original. This will gewt you to work in the morning with a de-fogged windshield. You'll need to rip apart the magic black box come spring time allong with replacing the hoses.

12-14-2003, 08:43 PM	#13
shuttermutt Don't say "Oops!", Doctor Join Date: Nov 2003 Location: Houston, TX Posts: 677	Most outstanding, Rage'nRat638! Your efforts are VERY appreciated! This will help a lot! __________________ 'Mutt 1968 CST LWB: R.I.P. 1967 Chevelle: TPI 454 beast 1967 C10 SWB: Claimed when Bumpster didn't put it on his list

12-14-2003, 09:17 PM	#14
OldSkool71 C/10 CLUB MEMBER Join Date: Jul 2003 Location: Lakewood, CA Posts: 993	Are those pics from the factory service manual? Damn I have to have one of those if so. __________________ -Ron-

12-14-2003, 09:55 PM	#15
rage'nrat638 Account Suspended Join Date: Mar 2003 Location: THE FALL GUY CHICAGO IL Posts: 5,883	BEST BOOK I HAVE BOUGHT SO FAR.................. Last edited by rage'nrat638; 07-12-2007 at 07:09 AM.

12-14-2003, 10:07 PM	#16
cwilli84 1FINE69 Join Date: Aug 2003 Location: Detroit, Michigan Posts: 239	I've got a 70 copy not any difference I noticed from a 69. Somebody wanna buy it. $20 +shipping __________________ Had a 69 swb fleetside 350zz3 w 400turbo trans oak lined bed with rhino coated sides red exterior. SOLD

12-14-2003, 11:36 PM	#17
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,450	Is there any difference between Chevy and GMC manuals? __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"



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12-14-2003, 11:43 PM	#18
cwilli84 1FINE69 Join Date: Aug 2003 Location: Detroit, Michigan Posts: 239	Not sure if anything significatly different but I have seen they have a differnet cover on them. __________________ Had a 69 swb fleetside 350zz3 w 400turbo trans oak lined bed with rhino coated sides red exterior. SOLD

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