mrite

My 99 F150 had the heat stuck on at all times, so I started researching the problem through different Ford forums. I found lots of helpful information. This is what has happened so far. I cut through into the plenum behind the glove box and found that the Blend door would not move from tge open heat position so I thought that the blend door was not broken. next I removed the Blend door actuator and looked at the bottom of the blend door and it is not broken, now i was able to go back through the Plenum and move the blend door to close off the heat. The motor looks to be good all the gears are in good condition. So here is my next question.
I came across a comment on another forum that said- If the air conditioner wasn't up to pressure then the blend door wouldn't work. does anybody know if this is correct? it would have saved me a lot of work.
Thank you

westtnfx4

Well I think that's it's vaccume operated....

mrite

there is some sort of vacuum canister close to the actuator but I don't know if it is for the actuator

westtnfx4

I'm not 100% but I know the majority of the system is ran by vaccume...someone else will have to chime in....