Heater controls

[Mschaffer92]

My friend has a 1996 gmc sierra ecsb and the air only comes from floor and doesnt blow very good. When u change the dials from the floor to something else it doesn't. Also she said it doesn't blow as good as mine. Any ideas?

 

[77Concours]

My friend has a 1996 gmc sierra ecsb and the air only comes from floor and doesnt blow very good. When u change the dials from the floor to something else it doesn't. Also she said it doesn't blow as good as mine. Any ideas?

I have this same problem in my 95. A friend of my dad had one of these trucks and said that it could be a dry rotted vaccum line under the dash somewhere. As for the air, is it just A/C or is it heat as well?

 

[hiredgun8]

Sound like the blend door actuator or the doors themselves.

 

[Mschaffer92]

It does it on heat and air. When you change them on the controls it only does it on the floor no where else. And it doesnt blow very hard on the floor either.

 

[hiredgun8]

Pull off the floor vent so you can see up in there.
Change the control and see if the doors move properly and seal off.
The rubber around one of my doors deteriorated so badly the door fell completely out.
Ordered all 3 from Rock Auto and it this is the best it's worked since I've had it.

 

[monstar_est87]

U got any part numbers for those blend doors..? Or a link..?

 

[outalne94z71]

I have this same problem in my 95. A friend of my dad had one of these trucks and said that it could be a dry rotted vaccum line under the dash somewhere. As for the air, is it just A/C or is it heat as well?

there are no vacuum lines on a gmt400 , they are all electric encoder motors on them for 88-94 a/c equipped trucks and all 95+

 

[hiredgun8]

155737 (15-5737)
155520 (15-5520)
1550552 (15-50552)
www.rockauto.com

These are the three that fit my 98. Use their online catalog to verify fitment on yours.

 

[Studio54]

I replaced all my blend door actuators and its worked great since. It was doing the same thing yours is. They're rather cheap too so it makes it an easy swap.

 

[98dieselburb]

Don't you have to pull the entire dash to do the rubber seals? I am pretty sure you don't for the actuators...but I am not sure about the seals