Alright well here is another one!!!!! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

79Chevypickup · 10-09-2003, 07:40 PM

Today in Houston, TX its been raining all day.....
I took my truck out and I cant seem to see through
the window, ya wanna know why?

MY DAMN defroster doesnt work!!!!!
My heater works and my vent works.....
There is air coming through the all the vents, except
the defroster vents on top of the dash....

Does anyone know what might be the problem or
a way to fix it so that air will come through the defroster
vents????

Any input will be appreciative!!!

Thanks!!

junkyardpartseeker · 10-09-2003, 07:47 PM

You need either to replace the switching cable that goes from the controls, to the air distribution box, or the flap on the box might be broke, and you will have to replace the air distribution box.

Tommy

79Chevypickup · 10-09-2003, 07:50 PM

So,
uh,
how could I troubleshoot to find out
what I need to replace or fix???
you know what I mean?

junkyardpartseeker · 10-09-2003, 07:54 PM

Here we go. Lay down on your floorboard on your right side. Look at the air box, it's long and from the pass side to a bit past your trans hump going toward the driver side. Use left hand and switch your controls from defrost thru all the positions. If you don't hear or see it switching down on the top of the box, your cable could be broke.

If not the cable, than the flap could have broke, or even frozen in place and that means going to the salvage and getting another one.

79Chevypickup · 10-09-2003, 07:56 PM

C R A P ! ! ! ! ! ! ! ! ! !

junkyardpartseeker · 10-09-2003, 07:59 PM

If it is your cable, that means pulling your instrument bezel to get the heater controls out. And hooking up another cable and sending it down thru the dash to clip it on top. Now, there is a plastic clip on top of the air distribution box that holds the cable on it to switch, that might just be broke.

If it is the flaps, the whole air distribution box will need to come out. And it has the heater core inside of it. So consult a repair manual on how to remove the box.

79Chevypickup · 10-09-2003, 08:02 PM

Your killing me!!!!

No more posts from you, you are making
me feel bad!!!!

Just kidding!!!

Thank you so much for the quick reply!!
I am going to pull my truck into the garage and
check it out in a little bit...

For real Tommy,

Thanks

junkyardpartseeker · 10-09-2003, 08:04 PM

Ok, if you got aol messenger, I am jypartseeker there. I have my repair manual in front of me and can help you thru it.

I found out a lot of this by replacing the heater core in my new burb I am getting ready to switch to. It was a pita to get it out, and then figure where all the screws were to get the core out.

Tommy

79Chevypickup · 10-09-2003, 08:06 PM

do you have any other Instant messengers?

yahoo?
msn?

**crossy** · 10-09-2003, 08:11 PM

79, everything that tommy said was right and if you feel it moving back there then your cable is OK it just may have moved in the bracket and does not open the inside flapper far enough. Before I pulled it apart you can physically try to move the metal arm farther in the same direction to see if it starts working then. DAVE

ItsNotABlazer · 10-09-2003, 08:30 PM

Heres a quick fix as long as it is not raining too hard when you do it.

Pull your vent window open a little where the air is directed across the dash and that will help clear the windshield sometimes if it isnt too bad. Not a real " fix" but might get you by until you find out whats really wrong with it and get it fixed.

Brad

79Chevypickup · 10-09-2003, 08:41 PM

tried that and found a problem.....

traffic sux, cause where there is rain there is traffic
where there is traffic there is no air movement!!

thanks for the input though.... seriously....

79Chevypickup · 10-09-2003, 08:57 PM

Do you know what that valve thing is for on the drivers side of the air box that sits on the tranny hump?
It has a wire or hose connected to it....
Also whats the deal with the metal flap thing on the very
bottom, I pulled it open with my fingers but still no air
goes up to the top of the dash (out the defroster vents)....

Thanks bro!!

**crossy** · 10-09-2003, 10:40 PM

well you live in TX. so I am assuming you have A/C . neither one of my current projects have A/C and i can't remember what one operates each control.
Also if you do have A/C then your controller switch is vacuum operated not mechanical like NON a/c trucks. if it has the vacuum switch then it is fairly common for that to go bad . check the main vacuum sorce to be sure you are getting vacuum there.
DAVE.

stan79chevy · 10-10-2003, 09:17 AM

Quote:

Originally posted by 79Chevypickup
Do you know what that valve thing is for on the drivers side of the air box that sits on the tranny hump?
It has a wire or hose connected to it....
Also whats the deal with the metal flap thing on the very
bottom, I pulled it open with my fingers but still no air
goes up to the top of the dash (out the defroster vents)....

Thanks bro!!

that is what was wrong with mine. the hose was unhooked, i just hooked it back up. there is also one of those canisters on the passenger side near the vent you may want to check that too.

MylilBowTie · 10-10-2003, 01:55 PM

Its a little late now but you can take the glove compartment out and see the top of the heatcore box where all the cables are and the vacumm lines.

79Chevypickup · 10-10-2003, 02:06 PM

they are good....
I just dont know what to do anymore......

10-09-2003, 07:40 PM	#1
79Chevypickup MY TRUCK IS FOR SALE!! Join Date: Sep 2003 Location: Pasadena, TX Posts: 292	Alright well here is another one!!!!! Today in Houston, TX its been raining all day..... I took my truck out and I cant seem to see through the window, ya wanna know why? MY DAMN defroster doesnt work!!!!! My heater works and my vent works..... There is air coming through the all the vents, except the defroster vents on top of the dash.... Does anyone know what might be the problem or a way to fix it so that air will come through the defroster vents???? Any input will be appreciative!!! Thanks!! __________________ 1979 Chevy LWB 350ci / 700R4 Edelbrock under the hood F O R S A L E OR T R A D E

10-09-2003, 07:47 PM	#2
junkyardpartseeker Registered User Join Date: Mar 2003 Location: Mabelvale, AR Posts: 695	defroster You need either to replace the switching cable that goes from the controls, to the air distribution box, or the flap on the box might be broke, and you will have to replace the air distribution box. Tommy __________________ junkyardpartseeker@sbcglobal.net

10-09-2003, 07:50 PM	#3
79Chevypickup MY TRUCK IS FOR SALE!! Join Date: Sep 2003 Location: Pasadena, TX Posts: 292	So, uh, how could I troubleshoot to find out what I need to replace or fix??? you know what I mean? __________________ 1979 Chevy LWB 350ci / 700R4 Edelbrock under the hood F O R S A L E OR T R A D E

10-09-2003, 07:54 PM	#4
junkyardpartseeker Registered User Join Date: Mar 2003 Location: Mabelvale, AR Posts: 695	troubleshoot Here we go. Lay down on your floorboard on your right side. Look at the air box, it's long and from the pass side to a bit past your trans hump going toward the driver side. Use left hand and switch your controls from defrost thru all the positions. If you don't hear or see it switching down on the top of the box, your cable could be broke. If not the cable, than the flap could have broke, or even frozen in place and that means going to the salvage and getting another one. __________________ junkyardpartseeker@sbcglobal.net

10-09-2003, 07:56 PM	#5
79Chevypickup MY TRUCK IS FOR SALE!! Join Date: Sep 2003 Location: Pasadena, TX Posts: 292	C R A P ! ! ! ! ! ! ! ! ! ! __________________ 1979 Chevy LWB 350ci / 700R4 Edelbrock under the hood F O R S A L E OR T R A D E

10-09-2003, 07:59 PM	#6
junkyardpartseeker Registered User Join Date: Mar 2003 Location: Mabelvale, AR Posts: 695	crap!!!!! If it is your cable, that means pulling your instrument bezel to get the heater controls out. And hooking up another cable and sending it down thru the dash to clip it on top. Now, there is a plastic clip on top of the air distribution box that holds the cable on it to switch, that might just be broke. If it is the flaps, the whole air distribution box will need to come out. And it has the heater core inside of it. So consult a repair manual on how to remove the box. __________________ junkyardpartseeker@sbcglobal.net

10-09-2003, 08:02 PM	#7
79Chevypickup MY TRUCK IS FOR SALE!! Join Date: Sep 2003 Location: Pasadena, TX Posts: 292	Your killing me!!!! No more posts from you, you are making me feel bad!!!! Just kidding!!! Thank you so much for the quick reply!! I am going to pull my truck into the garage and check it out in a little bit... For real Tommy, Thanks __________________ 1979 Chevy LWB 350ci / 700R4 Edelbrock under the hood F O R S A L E OR T R A D E

10-09-2003, 08:04 PM	#8
junkyardpartseeker Registered User Join Date: Mar 2003 Location: Mabelvale, AR Posts: 695	Good luck Ok, if you got aol messenger, I am jypartseeker there. I have my repair manual in front of me and can help you thru it. I found out a lot of this by replacing the heater core in my new burb I am getting ready to switch to. It was a pita to get it out, and then figure where all the screws were to get the core out. Tommy __________________ junkyardpartseeker@sbcglobal.net

10-09-2003, 08:06 PM	#9
79Chevypickup MY TRUCK IS FOR SALE!! Join Date: Sep 2003 Location: Pasadena, TX Posts: 292	do you have any other Instant messengers? yahoo? msn? __________________ 1979 Chevy LWB 350ci / 700R4 Edelbrock under the hood F O R S A L E OR T R A D E

10-09-2003, 08:11 PM	#10
crossy Oh,you can't buy that new Join Date: Apr 2000 Location: Pennsville,N.J. 08070, USA Posts: 2,039	79, everything that tommy said was right and if you feel it moving back there then your cable is OK it just may have moved in the bracket and does not open the inside flapper far enough. Before I pulled it apart you can physically try to move the metal arm farther in the same direction to see if it starts working then. DAVE __________________ "been there, done that, ruined the T-shirt". 2007 LBZ GMC Sierra, ECSB 2006 LM7 RCSB Silverado 98 Vortec project. 94,3500,6.5L 4L80 81 SWB GMC POS finally gone 73 Pinto, stock, w/CragarSS's-eww LOTS of Cummins trucks.

10-09-2003, 08:30 PM	#11
ItsNotABlazer The full convertible guy Join Date: Jul 2001 Location: Paris Texas Posts: 728	Heres a quick fix as long as it is not raining too hard when you do it. Pull your vent window open a little where the air is directed across the dash and that will help clear the windshield sometimes if it isnt too bad. Not a real " fix" but might get you by until you find out whats really wrong with it and get it fixed. Brad __________________ 2012 Kawasaki Vaquero (Lime Green) 2000 BMW 740iL 1995 Chevy ECSB riding on air 1975 GMC Jimmy 2WD lowered 4/6 1972 Chevy Trazer soon to be roadster 1965 Mustang 289/3 speed (friends dad bought it new) 1964 Chevy C10 (dad bought it new)

10-09-2003, 08:41 PM	#12
79Chevypickup MY TRUCK IS FOR SALE!! Join Date: Sep 2003 Location: Pasadena, TX Posts: 292	tried that and found a problem..... traffic sux, cause where there is rain there is traffic where there is traffic there is no air movement!! thanks for the input though.... seriously.... __________________ 1979 Chevy LWB 350ci / 700R4 Edelbrock under the hood F O R S A L E OR T R A D E

10-09-2003, 08:57 PM	#13
79Chevypickup MY TRUCK IS FOR SALE!! Join Date: Sep 2003 Location: Pasadena, TX Posts: 292	crossy!!!!! Do you know what that valve thing is for on the drivers side of the air box that sits on the tranny hump? It has a wire or hose connected to it.... Also whats the deal with the metal flap thing on the very bottom, I pulled it open with my fingers but still no air goes up to the top of the dash (out the defroster vents).... Thanks bro!! __________________ 1979 Chevy LWB 350ci / 700R4 Edelbrock under the hood F O R S A L E OR T R A D E

10-09-2003, 10:40 PM	#14
crossy Oh,you can't buy that new Join Date: Apr 2000 Location: Pennsville,N.J. 08070, USA Posts: 2,039	well you live in TX. so I am assuming you have A/C . neither one of my current projects have A/C and i can't remember what one operates each control. Also if you do have A/C then your controller switch is vacuum operated not mechanical like NON a/c trucks. if it has the vacuum switch then it is fairly common for that to go bad . check the main vacuum sorce to be sure you are getting vacuum there. DAVE. __________________ "been there, done that, ruined the T-shirt". 2007 LBZ GMC Sierra, ECSB 2006 LM7 RCSB Silverado 98 Vortec project. 94,3500,6.5L 4L80 81 SWB GMC POS finally gone 73 Pinto, stock, w/CragarSS's-eww LOTS of Cummins trucks.

10-10-2003, 01:55 PM	#16
MylilBowTie Right turn Clyde Join Date: Nov 2002 Location: Cincinnati, Ohio Posts: 2,911	Its a little late now but you can take the glove compartment out and see the top of the heatcore box where all the cables are and the vacumm lines.



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10-10-2003, 02:06 PM	#17
79Chevypickup MY TRUCK IS FOR SALE!! Join Date: Sep 2003 Location: Pasadena, TX Posts: 292	cables they are good.... I just dont know what to do anymore...... __________________ 1979 Chevy LWB 350ci / 700R4 Edelbrock under the hood F O R S A L E OR T R A D E

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