ok first off the truck is not a 1987 its an 86 302 it does have ac , got a slight problem the heater will not switch off of the vents wont switch to defrost or floor, i live in iowa and the defroster is a pretty critical piece if you all could give me any pointer it would be greatly appreciated

 

Hi . the doors that control the direction of the air flow ( vent, floor,defrost ) are control by vacum lines . make sure they r connect it, and working wright. the lines on my 93 one its black and the other its withe.

 

There is vacuum present I can see te vacuum motors move but no change in the direction of air, another thing is air blows harder out the 2 vents on the passnger side than on the drivers side any ideas as to how to fix it would be greatly appreciated!!

 

i live in iowa to either you can spend the time amd find all the vacuum lines or you can wire the blend door open till you have enough time to find everything

 

behind and to the left of the glove compartment door is a wire with a looped end that fits over a plastic pin that move the vanes in the control box. See if the connector or pin is broken or sheared off


EDIT now that i think of it. the control i described is for the temperature, not the defroster,

 

I know there is vacuum there I can physically watch the little motor diaphram move when u switch the control from vent to floor to whatever but the direction of the air does not change

 

I think the passenger side blowing harder is just because the blower motor is located on that side...could be wrong, but I've noticed that in my truck also

 

I just realized u live in sioux city I too live there

 

The wire behind the glove box tha A W Smith is talking about i think its to control the door for hot or cold. thats how my 93 f150 its. going back to bacum line if u can see the diaphram move , can u heard the doors for the air flow move.They maybe broken or lose inside or diaphrame could have a leak. disconnect the vacum lines and move them by hand and check i u can heard something moving inside

 

what part of sioux city i live in morningside on leech