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73-87 Chevy _ GMC Trucks => Interior & Equipment => Heating, Ventilation & Air Conditioning (HVAC) => Topic started by: 81chevyskullc10 on November 26, 2011, 07:11:51 pm

Title: Defrost issue
Post by: 81chevyskullc10 on November 26, 2011, 07:11:51 pm
I Have an 81 Chevy C10, 305, truck had ac, no ac now. found the door that switches the heat from going defrost or floor. can i adjust the rod on top to make the door close all the way. my problem is when i turn defrost on the door stays at least 2 inches open. i noticed the rod on top and its threaded. was hoping i can adjust this to make the door shut?
Title: Re: Defrost issue
Post by: zieg85 on November 26, 2011, 07:31:16 pm
Does it still have the factory AC dash and controls?  If it does is the vacuum still hooked up?
Title: Re: Defrost issue
Post by: 81chevyskullc10 on November 26, 2011, 09:41:50 pm
yes everything is still there, i figured out that the flap under the dash is getting stuck when it goes to shut.  tried adjusting the threaded rod but this did not help. any idea how to get the flap not to stick?

Title: Re: Defrost issue
Post by: bake74 on November 27, 2011, 09:33:13 am
     Disconnect the control rod and see if you can manually close and open all the way, to make sure something is not impeding it's movement.  If not make sure to spray a little wd-40 or the like on the hinges and what not.
      Also make sure when it is disconnected you move the control rod and make sure it has the full range of motion.
      I believe the 81 still uses the control rod and not straight vacuum.
Title: Re: Defrost issue
Post by: HAULIN IT on November 27, 2011, 04:06:34 pm
     Disconnect the control rod and see if you can manually close and open all the way, to make sure something is not impeding it's movement.  If not make sure to spray a little wd-40 or the like on the hinges and what not.
      Also make sure when it is disconnected you move the control rod and make sure it has the full range of motion.
He's got you covered. I had a similar situation several years ago on the "junker" I posted pictures of the other day. What I did was crude, but effective. After figuring out that "something" was stopping the door INSIDE the box with methods described above I took a 2" holesaw & cut through the box, stuck a magnet in there & pulled out a small pipe nipple (I suspect that at some point it was placed up on the dash & made it's way down the duct system to the box). A piece of duct tape over the hole & we were "Good to Go!". While I'm not usually a fan of crude/hack ways of doing things, it worked well in this case & fit the truck at this point in it's life. The piece could also be glued back in, finished & painted for a nicer appearance...still a whole lot quicker & easier than removing the unit to find the problem. If you find that your convinced that something is IN the box let me know & I'll post you a picture of where a drilled (I had a spare box off of a truck to look inside to plan the best, "most likely" spot to find the problem & get whatever out. Good Luck! Hopefully it's something simple. Lorne   
Title: Re: Defrost issue
Post by: 81chevyskullc10 on November 27, 2011, 06:42:07 pm
ya it sticks about 2 inches from being shut. i tried adjusting rod but its not any better. I see where it sticks now, so all i need to do is find out why it is sticking lol thanks guys