I cant figure out what this part is called. Its on top of the heater blower motor, right next to the heater core send and return lines. I know it has something to do with the in-cab air controls. Its for the flap for the vent or something. It also has a vacuum line (has been severed before I got the truck). No electrical connections. I cant find out what it is from going to Advance Auto, LMC truck or my Haynes repair manual. the piece that attaches to the cylinder part to the flap part rusted off and I havent gotten another one from the junk yard yet.

What is it? and could it be affecting why my heat doesn't really work anymore?

 

It is common for the white line to break.

The part you are asking about is a vacuum motor for the blend door. It definitely is related to your heater not working right. It regulates which vents the air comes out. The hot cold is done by a cable.

 

Thanks, I appreciate it. Ill try to track one down so my heat will actually work right

 

Not true.

It is a vacuum motor but it controls the outside air door to the heater box.
Has nothing to do with the blend door, that is cable controlled.
The vent/floor door is also controlled by a vacuum motor.
The white vacuum line does break a lot but when it breaks all air will switch to the defrost vents when you accurate the truck.

 

I just meant that it was a vacuum motor for the air and if there is a vacuum leak, it would cause issues with the vents. I guess I didn't word that well.

 

I found a semi decent one from the junk yard. Most of them all had the white line just crumbling apart. I put it on and it might've helped but I think my main problem originally was I was just low on coolant, Boy I feel stupid right about now, I was over a gallon low, radiator has a leak so I tried to stop up the leak while I was working on it. Good news is I got heat now!