ok every one seems to think when there is no heat it is a clogged heater core, that my be possible, but has anyone come across a malfuntioning blend door due to a broken plastic gear. prior to pulling the dash apart what would be the best way to diagnose this problem.

 

its gotta be done w/ a scan tool... measure values from the scan tool can tell wha position each door motor is in...

or you could disconnect the lines going in and out the heater core and blow compressed air in it.

pinch off the coolant lines tho.

 

thanks i didn't know a scan could tell what position the doors are in