Wife's 1999 GMC Sierra blow's cold air only regardless of the temp. setting. Hot water circulating through core. Direction control works fine.
I'm thinking that the door that regulates the temp isn't working.
Is there an easy way to find out what's going (without tearing the whole dash out)? Or do I just take it to the dealer and hope he doesn't rip me to bad.
I do as much work on my vehicles as I can but I'm getting to the age where I can't crawl around inside and under like I use to. Plus we're just finishing up 6 straight days of rain and all of my work is done outside.

Thanks in advance for any help.

 

should be able to see cable movement under the dash from the passengers side, flash light and mirror. have somebody move the temp control lever back and forth gently to see if it moves the door

 

I'm with oldblue on this. Have someone work the temp control while you check under the dash to see if it's operating.

My opinion. I just can't understand someone wanting to take a 14 year old car to a dealership. An independant garage or AC shop would be my choice. Much cheaper and the work will be as good or better depending on the shop you choose.

 

firemangeorge, I only have one garage and I'm my only customer, well I will work on my wife's Sunfire GT but that's it. my wrenching days for work are done, 41 years was enough! and I agree independent shop and not a dealership

 

Does the blower work on all settings or just on low and high?

 

Blower works fine on all speeds. The control for the defrost, dash or floor works fine. There isn't a cable just a pot that controls a motor driven door allowing hot, cold or mix. The main reason I go to the dealership is because we don't have a decent shop around here that I can trust. And yes I trust my dealer but he can be a little costly.
Thanks for your input, it's greatly appreciated.

 

It might just be your blower/heat resistor

That is almost common in GMC/Chevy trucks and I've also had to replace them in Chryslers too

 

Is this the potentiometer on the dash panel? How difficult is it to replace?
My main fear is that the dash has to come out and though my mechanical level is pretty high, this is something I would leave to the folks that do it every day. Unfortunately there is not a decent shop for 25-30 miles (one I would trust), so I use the dealer for the complicated jobs. They are good but as I stated earlier, they can be pricey. (My wife likes them because they don't talk down to her).
Rod Run, thank you for time and advice. One of the reasons this forum is so great is because of the depth of knowledge present here. Again, thank you all.