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73-87 Chevy _ GMC Trucks => Interior & Equipment => Heating, Ventilation & Air Conditioning (HVAC) => Topic started by: DCustom on December 05, 2013, 10:07:57 pm

Title: defrost duct
Post by: DCustom on December 05, 2013, 10:07:57 pm
I noticed my defrost duct wasnt all the down on the box and i cant get it flush. Anyone else had this issue.
Title: Re: defrost duct
Post by: Captkaos on December 06, 2013, 11:57:43 am
All of them are like this.  It is normal. 

http://forum.73-87chevytrucks.com/smforum/index.php?topic=22750.0
http://forum.73-87chevytrucks.com/smforum/index.php?topic=21879.0
http://forum.73-87chevytrucks.com/smforum/index.php?topic=12793.0
http://forum.73-87chevytrucks.com/smforum/index.php?topic=23549.0
Title: Re: defrost duct
Post by: DCustom on December 06, 2013, 01:23:32 pm
Thanks for the info. I have looked all morning for a piece of foam or something that may have fell out. Have started constructing additional plastic to weld or glue. Again I thank you for assuring me that im not crazy......
Title: Re: defrost duct
Post by: Captkaos on December 08, 2013, 12:03:30 pm
Just tape it with some foil duct tape.
Title: Re: defrost duct
Post by: DCustom on December 08, 2013, 12:39:05 pm
Yes sir....I worked several hours and thats what I ended up doing...Thanks for the info....this site and the great people on here may make this restore alot easier....till next time
Title: Re: defrost duct
Post by: rockygryphon on December 16, 2013, 06:52:04 pm
I, too, have been wrestling with this problem of the defrost duct. 

I put some duct tape around the gap. 
In order to do that, I:
removed the glove compartment (four screws on bottom [3 4 me]),
removed the vent duct right behind the glove compartment (3? screws),
pulled down the long duct that runs at the bottom of the dashboard,
cut a few strips of duct tape and using a flashlight and knife, shoved a strip for each side into place and pressed it into place.

I noticed a big door where I removed that duct behind the glove compartment, that operates to route air to the defrost vent.
There is also another door below the defrost duct visible after removing one screw and pulling the floor ducts off the bottom.
Since my vacuum system is undoubtedly dead, like my A/C, and I don't care, I plan to:
Zip tie the bottom flap open so air goes up to the defrost vents.
Zip tie the interoperating pair of doors closed so they route air toward the defrost vent/door.

When I have to drive in hot weather sometime next year, maybe then I'll fix the A/C, vacuum, etc.

It's just plain dangerous driving when you have to scrape the windshield and windows on the inside to see!

I think this is all I need for a poor man's defrost (aside from heat and a working fan, which I believe I have).

Am I missing anything?
Title: Re: defrost duct
Post by: rockygryphon on December 17, 2013, 02:59:14 pm
so I zip tied the pair of doors so they're directing air toward the defrost conduit.

I just pulled the bottom door's catch off the vacuum pod rod so it would fall, close flow to the floor, and direct air to the defrost conduit.

It's seems like there's more flow from cold than hot so I'm assuming the only things to do now are;
clean out debris
replace the blower motor

Now I  just have to find where I can remove debris from.
Title: Re: defrost duct
Post by: rockygryphon on December 27, 2013, 08:57:50 pm
Ok so no one seems to be interested or mind since maybe it was rude of me to hijack this thread I guess, but here's how it's finally turned out.
The weather was bearable today, so I bought a new 1994 GMC 1500 4X4 BLOWER MOTOR from Oreilly's Auto and installed it.  It blew a tornado into my cab.  For some unknown reason, (freezing cold maybe), the previous junk yard blower motor I had installed, had the short cage... inadequate.  I can now feel the defrost wind through my pair of plastic gloves and it sounded like real wind instead of a distant breeze.  So this time, the new motor in combination with setting the doors to defrost and taping the gaps and openings, makes the defrost more powerful than a 2013 car!  Now if I can figure out how to make sure I get complete re-circulation to avoid outside odors, and get the diesel engine to heat up faster in winter... plan to install a eberspacher diesel heater eventually...
Title: Re: defrost duct
Post by: Captkaos on December 29, 2013, 09:10:40 am
To keep the outside air from coming in you need to block off the kick vents.  To get the motor warmed quicker install a block heater.

I don't think your posts were ignored, I read them.

Chris Lucas
73-87chevytrucks.com
captkaoscustoms.com
squarebody.biz

Title: Re: defrost duct
Post by: rockygryphon on February 27, 2014, 03:58:13 pm
Hey I'm glad you read them, Captkaos.  On my 85 K10 Silverado with AC, I have one kick vent on the right controlled by vacuum only.  I disconnected that and left the flap open.  I taped the cowl vents closed with duct tape.  I still get odors in the cab, but I think it's from the big draft through the doors.  I'll probably tape the door vents closed next, and maybe finally tape closed those rust holes in the doors. bleh.
Title: Re: defrost duct
Post by: VileZambonie on February 27, 2014, 06:12:20 pm
94 K10 blower motor pn =35334
85 K10 blower motor pn =35334

Not sure why everyone thinks  94 blower motor is an upgrade. You're just replacing a worn out unit