Heat duct issues. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**rs74** · 11-07-2013, 11:43 PM

Since I bought the 85 k30 I have been wondering why there is only one duct in the dash not including the defrost duct. They had a custom deluxe dash bezel that had no vent in it stuck in the dash pad eliminating two vents. The one buy the headlight switch was covered up by a piece of metal. This is an A/C truck.

I tore the glovebox and dashpad off tonight to find that someone had taken the top half of the duct work out. So all there was is defrost and floor. There was air blowing on the underside of the dash the way they had it set up. So I am taking the needed pieces from another cab and putting it back together the right way. Oh and there was a white plastic clip that holds a threaded rod that goes to the blend door. The white plastic piece was missing so fixed that too.

What I am wondering while putting this back together is what are you guys doing for the big gap where the defrost duct hooks to the main box. Are you putting tape around it to seal it off so you get max airflow through the defrost? Here is a pic of what I am talking about. Both my K30 and K10's were like this. I can drop the defrost duct down but I would have to unbolt it from the dash so it can slide down. But if I do that then I don't know that the defrost ducts will blow air up through the dashpad.

79Betty · 11-08-2013, 07:21 AM

Mine's got gorilla tape. Black so not as noticeable.

Rubble · 11-08-2013, 10:09 AM

I just finished replacing the heater core on my crew last month,had all the ducting out to clean mouse sh&t out.I have the same gap in it,most of my others do to & it doesn't seem to affect the airflow on defrost that bad anyway.Had a morning two days ago of -20 deg C & it cleared windshield great!! I replaced the fan motor too,that really helped airflow...that and getting critter nests out!!

**rs74** · 11-08-2013, 10:09 AM

I was suprised to see that much gap right there. Everything else seems to have a fairly tight connection on it.

motornut · 11-08-2013, 05:14 PM

I've seen that gap taped before, but can't you loosen and move the box up?

**rs74** · 11-08-2013, 08:32 PM

Quote:

Originally Posted by motornut

I've seen that gap taped before, but can't you loosen and move the box up?

The lower box is bolted to the firewall. I am not sure if there is enough play if you loosen it and try to slide it up.

motornut · 11-08-2013, 09:55 PM

Quote:

Originally Posted by rs74

The lower box is bolted to the firewall. I am not sure if there is enough play if you loosen it and try to slide it up.

there is slight play when loosend up

11-07-2013, 11:43 PM	#1
rs74 Senior Member Join Date: Jun 2010 Location: Illinois Posts: 2,957	Heat duct issues. Since I bought the 85 k30 I have been wondering why there is only one duct in the dash not including the defrost duct. They had a custom deluxe dash bezel that had no vent in it stuck in the dash pad eliminating two vents. The one buy the headlight switch was covered up by a piece of metal. This is an A/C truck. I tore the glovebox and dashpad off tonight to find that someone had taken the top half of the duct work out. So all there was is defrost and floor. There was air blowing on the underside of the dash the way they had it set up. So I am taking the needed pieces from another cab and putting it back together the right way. Oh and there was a white plastic clip that holds a threaded rod that goes to the blend door. The white plastic piece was missing so fixed that too. What I am wondering while putting this back together is what are you guys doing for the big gap where the defrost duct hooks to the main box. Are you putting tape around it to seal it off so you get max airflow through the defrost? Here is a pic of what I am talking about. Both my K30 and K10's were like this. I can drop the defrost duct down but I would have to unbolt it from the dash so it can slide down. But if I do that then I don't know that the defrost ducts will blow air up through the dashpad. Attached Images __________________ Roy 85 Short Bed Silverado- Work in progress. http://67-72chevytrucks.com/vboard/s...d.php?t=564818 1987 R10 shortie

11-08-2013, 07:21 AM	#2
79Betty Registered User Join Date: Jan 2013 Location: Jasper, IN Posts: 948	Re: Heat duct issues. Mine's got gorilla tape. Black so not as noticeable. __________________ When in doubt, throttle it out! 1974 Chevrolet Custom K20 2005 Ford Ranger Edge 1985 Chevrolet Custom Deluxe C10

11-08-2013, 10:09 AM	#3
Rubble Registered User Join Date: Feb 2012 Location: Big Valley. Alberta Posts: 674	Re: Heat duct issues. I just finished replacing the heater core on my crew last month,had all the ducting out to clean mouse sh&t out.I have the same gap in it,most of my others do to & it doesn't seem to affect the airflow on defrost that bad anyway.Had a morning two days ago of -20 deg C & it cleared windshield great!! I replaced the fan motor too,that really helped airflow...that and getting critter nests out!! __________________ 1977 Chev C30 454/465/14ff DRW 1974 Chev C20.350/465/14ff " Rock n Roll ain't noise pollution"

11-08-2013, 10:09 AM	#4
rs74 Senior Member Join Date: Jun 2010 Location: Illinois Posts: 2,957	Re: Heat duct issues. I was suprised to see that much gap right there. Everything else seems to have a fairly tight connection on it. __________________ Roy 85 Short Bed Silverado- Work in progress. http://67-72chevytrucks.com/vboard/s...d.php?t=564818 1987 R10 shortie

11-08-2013, 05:14 PM	#5
motornut 78K & 79C Jimmys Join Date: Nov 2009 Location: Ottawa Ont CANADA Posts: 7,901	Re: Heat duct issues. I've seen that gap taped before, but can't you loosen and move the box up? __________________ John 1978 GMCJimmy4X4-350/203 1979 GMCJimmy4X2-305/350



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