1996 jimmy no heat, is it the blend door?

i first thought that i needed to replace my heater core. because i dont have any heat.

a friend of mine came over to help and he said that he couldn't hear the blend door move?
key was in the ON position, but the engine wasn't running.

can you "hear" the blend door move on your truck?
how can i tell the blend door is moving or not?

Someone correct if I'm wrong, but I'm pretty sure the blend door requires vacuum to move. So it should only move with the engine running. Here's a simple test... Start the vehicle. With the fan setting on high and coming out the vents, move blend knob from cold to heat and listen.. Did the fan change sounds (louder/quieter)? If you can hear a difference between warm and cool, you may have a stopped up heater core, which was a quite common thing on my blazer. Just remove the heater hoses from the engine, and flush them with a water hose until clear water comes out. Then just hook them back up the same way they came off.

that's what i thought. but my friend said that it's an electric motor that works the blend door

That's possible. I know the 94's use a cable, but I'm unsure of the '96. If no one has answered by tomorrow, I will check my dealer computer and see how it's controlled. If it is an electric motor, i suspect the switch to be bad.

just wanted you all to know.

the electrical plug that controls the blend door was unplugged from the heater control head

Ha Ha!! yeah, that'll do it..