A/C heater vent not blowing front dash - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ahm_3333 · 12-24-2009, 11:24 PM

I'm new and need some help. I have an 82 gmc 1/2 that I cannot fix, it blows a/c and heat from below under the dash strong, but blows very little in the vents that are in the dash for some reason, does anyone know what it could be.....help....

Thanks
AD....

Prong · 12-25-2009, 04:30 AM

It's probably the blend door in the heater box under the dash (below the glovebox), or you have arotted or disconnected vacuum line to an actuator that controls the air flow.

ahm_3333 · 12-26-2009, 12:35 AM

Thanks for your input

motornut · 12-26-2009, 06:10 AM

hi just above the gas pedal make sure there is a vac line on the (floor to defrost)diaphram,and on the pass side remove the duct work to access and check if this clip is broke door won't work to close vents

ahm_3333 · 12-28-2009, 12:03 PM

Thanks for the info.....

AD......

kevinr1970 · 01-05-2010, 01:31 PM

Quote:

Originally Posted by motornut

hi just above the gas pedal make sure there is a vac line on the (floor to defrost)diaphram,and on the pass side remove the duct work to access and check if this clip is broke door won't work to close vents

My problem in my '82 is that when I swtch it over to defrost, it barely comes up through the top vents but seems to all come out through the front vents. When on heater it seems fine on the floor.
Should I be looking at the same thing?

Any place I can look that explains the mechanics of how the HVAC system works?

Justins76 · 12-26-2009, 05:38 PM

I have that same problem and it turned out to be the plastic part broken just like in the pic above. Does anyone know where to buy a replacement part?

dswancutt · 12-27-2009, 10:40 AM

They are still available from GM. I bought a whole package of 5 on 12/10/09. The part number is 3018715 and they list for $2.25 each. I just bought the whole package so I have some spares for the other trucks.
Hope this helps.

Justins76 · 12-28-2009, 06:59 PM

Thanks for the part #

jdclemons · 01-04-2010, 06:23 PM

Hi guys im new and i ran across this post and im having a similar problem. My heater/ac blows buts it comes out in both places defrost and front vents at the same time. I replaced that clip shown in the picture above but it seems like i have no vacuum. I have a 1987 silverado efi throttle body. Can anyone tell me exactly where it gets its vacuum from.

jpenny376 · 07-18-2012, 10:47 AM

Hey motornut can u move that bundle of wires and get a pic of that top part? The person who had my truck before me decided to take the springs and that rod with the screw end off. I guess they did not pay attention to how they took it apart cuz it was just laying on top.

**RandyP** · 07-18-2012, 11:03 AM

Hang on, he has to get the runway cleared so he can reach 88mph!

motornut · 07-18-2012, 12:26 PM

a little from the side?

jpenny376 · 07-18-2012, 01:32 PM

Little more left??? Other end of that rod plz

motornut · 07-19-2012, 08:57 AM

Quote:

Originally Posted by jpenny376

Little more left??? Other end of that rod plz

sorry didn't get any that way

jpenny376 · 07-19-2012, 09:49 AM

Darn.....thanks anyway

jpenny376 · 07-19-2012, 09:50 AM

any idea where to get a look at it???

motornut · 07-19-2012, 10:03 AM

no sorry the jimmys don't have AC
and that truck is about an hour away
going for scrap soon....

jpenny376 · 07-19-2012, 10:07 AM

ok thanks

12-24-2009, 11:24 PM	#1
ahm_3333 Registered User Join Date: Dec 2009 Location: Dallas, TX Posts: 4	A/C heater vent not blowing front dash I'm new and need some help. I have an 82 gmc 1/2 that I cannot fix, it blows a/c and heat from below under the dash strong, but blows very little in the vents that are in the dash for some reason, does anyone know what it could be.....help.... Thanks AD....

12-25-2009, 04:30 AM	#2
Prong Registered User Join Date: May 2007 Location: CO Posts: 398	Re: A/C heater vent not blowing front dash It's probably the blend door in the heater box under the dash (below the glovebox), or you have arotted or disconnected vacuum line to an actuator that controls the air flow.

12-26-2009, 12:35 AM	#3
ahm_3333 Registered User Join Date: Dec 2009 Location: Dallas, TX Posts: 4	Re: A/C heater vent not blowing front dash Thanks for your input

12-26-2009, 06:10 AM	#4
motornut 79/78 Jimmys Join Date: Nov 2009 Location: Ottawa Ont CANADA Posts: 5,707	Re: A/C heater vent not blowing front dash hi just above the gas pedal make sure there is a vac line on the (floor to defrost)diaphram,and on the pass side remove the duct work to access and check if this clip is broke door won't work to close vents Attached Images __________________ John 1976 Terry Taurus http://67-72chevytrucks.com/vboard/s...d.php?t=431859 2002 Fleetwood Prowler 1978 Suburban 4X2 - hit while parked RIPzez 1978 Olds Cutopless - CanadaDayCar http://youtu.be/DgsjkULFiHo 1978 GMC Jimmy 4X4 -350/203 NOT stock Tremclad Fire Redhttp://67-72chevytrucks.com/vboard/s...d.php?t=421767 1979 GMC Jimmy 4X4 -350/203 with plow http://67-72chevytrucks.com/vboard/s...=421767&page=2 1979 GMC Jimmy 4X2 -305/350 stockish http://67-72chevytrucks.com/vboard/s...=1#post5200107 1987 Suburban 4X4 - writeoff hit while parked RIPzez 1988 Suburban 4X4 - writeoff hit while parked RIPzez http://67-72chevytrucks.com/vboard/s...d.php?t=417457 1989 Suburban 4X2 - square igloo/SOLD 2003 Grand Am 2.2 his DD 2005 Malibu 2.2 her DD Love em low,but get me higher

12-28-2009, 12:03 PM	#5
ahm_3333 Registered User Join Date: Dec 2009 Location: Dallas, TX Posts: 4	Re: A/C heater vent not blowing front dash Thanks for the info..... AD......

12-26-2009, 05:38 PM	#7
Justins76 OutOfMyMind & I'llNeverKnowWhy Join Date: Apr 2004 Location: Another world, some other time Posts: 568	Re: A/C heater vent not blowing front dash I have that same problem and it turned out to be the plastic part broken just like in the pic above. Does anyone know where to buy a replacement part? __________________ -Justin-Out of my mind and I'll never know why 1976 Chevrolet Silverado C10 350 4bbl / TH350 Big10 longbed 1986 Pontiac Firebird T-Top 5.0L LG4 700R4 WS6 1992 Pontiac Firebird T-Top 5.0L TBI 700R4 My cardomain page I don't like to save, it's more fun to spend!!

12-27-2009, 10:40 AM	#8
dswancutt Registered User Join Date: Jul 2003 Location: Franklin, NE Posts: 387	Re: A/C heater vent not blowing front dash They are still available from GM. I bought a whole package of 5 on 12/10/09. The part number is 3018715 and they list for $2.25 each. I just bought the whole package so I have some spares for the other trucks. Hope this helps.

12-28-2009, 06:59 PM	#9
Justins76 OutOfMyMind & I'llNeverKnowWhy Join Date: Apr 2004 Location: Another world, some other time Posts: 568	Re: A/C heater vent not blowing front dash Thanks for the part # __________________ -Justin-Out of my mind and I'll never know why 1976 Chevrolet Silverado C10 350 4bbl / TH350 Big10 longbed 1986 Pontiac Firebird T-Top 5.0L LG4 700R4 WS6 1992 Pontiac Firebird T-Top 5.0L TBI 700R4 My cardomain page I don't like to save, it's more fun to spend!!

01-04-2010, 06:23 PM	#10
jdclemons Registered User Join Date: Jan 2010 Location: Eatonton, GA Posts: 14	Re: A/C heater vent not blowing front dash Hi guys im new and i ran across this post and im having a similar problem. My heater/ac blows buts it comes out in both places defrost and front vents at the same time. I replaced that clip shown in the picture above but it seems like i have no vacuum. I have a 1987 silverado efi throttle body. Can anyone tell me exactly where it gets its vacuum from.

07-18-2012, 10:47 AM	#11
jpenny376 Registered User Join Date: Jul 2012 Location: paradise tx Posts: 6	Re: A/C heater vent not blowing front dash Hey motornut can u move that bundle of wires and get a pic of that top part? The person who had my truck before me decided to take the springs and that rod with the screw end off. I guess they did not pay attention to how they took it apart cuz it was just laying on top.

07-18-2012, 11:03 AM	#12
RandyP Getting Old; Going Broke Join Date: Apr 2010 Location: Owasso Oklahoma Posts: 2,408	Re: A/C heater vent not blowing front dash Hang on, he has to get the runway cleared so he can reach 88mph! __________________ *Why is every used 350 sbc out of a corvette?* There's only two things that excite a man, expensive toys and real expensive toys. *VEGETARIAN: That's an old Indian word meaning "I don't hunt so good."* When the going gets tough, switch to power tools.

07-18-2012, 12:26 PM	#13
motornut 79/78 Jimmys Join Date: Nov 2009 Location: Ottawa Ont CANADA Posts: 5,707	Re: A/C heater vent not blowing front dash a little from the side? Attached Images __________________ John 1976 Terry Taurus http://67-72chevytrucks.com/vboard/s...d.php?t=431859 2002 Fleetwood Prowler 1978 Suburban 4X2 - hit while parked RIPzez 1978 Olds Cutopless - CanadaDayCar http://youtu.be/DgsjkULFiHo 1978 GMC Jimmy 4X4 -350/203 NOT stock Tremclad Fire Redhttp://67-72chevytrucks.com/vboard/s...d.php?t=421767 1979 GMC Jimmy 4X4 -350/203 with plow http://67-72chevytrucks.com/vboard/s...=421767&page=2 1979 GMC Jimmy 4X2 -305/350 stockish http://67-72chevytrucks.com/vboard/s...=1#post5200107 1987 Suburban 4X4 - writeoff hit while parked RIPzez 1988 Suburban 4X4 - writeoff hit while parked RIPzez http://67-72chevytrucks.com/vboard/s...d.php?t=417457 1989 Suburban 4X2 - square igloo/SOLD 2003 Grand Am 2.2 his DD 2005 Malibu 2.2 her DD Love em low,but get me higher

07-18-2012, 01:32 PM	#14
jpenny376 Registered User Join Date: Jul 2012 Location: paradise tx Posts: 6	Re: A/C heater vent not blowing front dash Little more left??? Other end of that rod plz

07-19-2012, 09:49 AM	#16
jpenny376 Registered User Join Date: Jul 2012 Location: paradise tx Posts: 6	Re: A/C heater vent not blowing front dash Darn.....thanks anyway

07-19-2012, 09:50 AM	#17
jpenny376 Registered User Join Date: Jul 2012 Location: paradise tx Posts: 6	Re: A/C heater vent not blowing front dash any idea where to get a look at it???



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07-19-2012, 10:03 AM	#18
motornut 79/78 Jimmys Join Date: Nov 2009 Location: Ottawa Ont CANADA Posts: 5,707	Re: A/C heater vent not blowing front dash no sorry the jimmys don't have AC and that truck is about an hour away going for scrap soon.... Attached Images __________________ John 1976 Terry Taurus http://67-72chevytrucks.com/vboard/s...d.php?t=431859 2002 Fleetwood Prowler 1978 Suburban 4X2 - hit while parked RIPzez 1978 Olds Cutopless - CanadaDayCar http://youtu.be/DgsjkULFiHo 1978 GMC Jimmy 4X4 -350/203 NOT stock Tremclad Fire Redhttp://67-72chevytrucks.com/vboard/s...d.php?t=421767 1979 GMC Jimmy 4X4 -350/203 with plow http://67-72chevytrucks.com/vboard/s...=421767&page=2 1979 GMC Jimmy 4X2 -305/350 stockish http://67-72chevytrucks.com/vboard/s...=1#post5200107 1987 Suburban 4X4 - writeoff hit while parked RIPzez 1988 Suburban 4X4 - writeoff hit while parked RIPzez http://67-72chevytrucks.com/vboard/s...d.php?t=417457 1989 Suburban 4X2 - square igloo/SOLD 2003 Grand Am 2.2 his DD 2005 Malibu 2.2 her DD Love em low,but get me higher

07-19-2012, 10:07 AM	#19
jpenny376 Registered User Join Date: Jul 2012 Location: paradise tx Posts: 6	Re: A/C heater vent not blowing front dash ok thanks

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