I was wiring a new speaker to driver door and during process had to turn key on several times for testing. It appears the blend door stopped engaging cause i normally hear the door engage when i turn vehicle on. Once done with the speaker i noticed AC was blowing cold out the top only and not out of front vents no matter what i did with controls. I had the blend door replaced some 8 years ago. Would it be safe to say it went out again? or perhaps that one small plastic piece that is known to crack?? This is for a 2001.

 

Could be a vacuum issue there is a thread stickied at the top called "Wild Vents"

 

you're right, will check the vacuum hoses and check valves. i've had the wild vent issue before.

 

sure enough, just like last time, one of the two vacuum lines that go into the cab was disconnected. all is good.

 

Glad you got it fixed! Sometimes it is that simple!