heat, vent, defrost

[chris989]

Hello All,

I searched and read a few post about the heat/ac not switching from defrost to floor or vent. Most post say the diaphragm that actuates the damper door has failed.

I am not getting vacuum to the diaphragm. i have vacuum under the hood to where is goes through the firewall.

is there another point of failure i should consider before i tear my dash apart? Does the main control in the dash sometimes fail or become clogged? When i switch from heat to defrost i can here one of the diaphragms move but i still get 90% of the air out of the vents.


Additional note,
I feel i have a leak somewhere because now if i am going downhill with my foot off the gas the engine will surge.

Thanks,
Chris