my truck will not work on defrost mode, all blend door actuators and recirculation door actuators work and all vaccume lines appear to be working fine with no leaks or breaks. don't know if it's a control **** issue or what, any suggestions?

 

I think the blend door and mode door is operated by Electric.... that is how it is on my 2004.5 I had a broken mode door it was stuck on vents and you had to switch the **** to vents and then to defrost and sometimes it would work. Sometimes it wouldn't... If its a mode/blend door they are a PITA to change.. EVERYTHING has to come out dashboard steering column and A/c freon 134A..
Also my may just have a Pen or something down in the vents and stopping the mode door from moving to defrost.. But you will need to make sure its the door or Actuator or the switch..

 

Yeah i talked to the dealer and he thinks it's a mode door too but i'm going to get a vacuume check done first and then check my selector mod first before i go ripping into the dash. Hope it's not that serious thx...

 

hope so too is your electric or does it run off of vacuum? I am pretty sure they are electric actuators since in 99 they electric..