My heater only gets luke warm. The vacuum motor under the hood in front of the fan motor does not work in any position of the selector ****. I disconnected it and twist tied it open, the heater puts out more heat, but is still not HOT like it should be. I think this may be a recirc door, because I can see the fan blades under the dash thru it. Motor temp is OK and both heater hoses are HOT. Is there a source for a vacuum diagram that shows the heater/vent vacuum lines? Not knowing exactly what they control and what controls them makes it hard to trouble shoot.

'96 F250/460/5spd/reg cab

Thanks

 

This diagram has some more vaccuum motors attached to the heater switch assembly.

that may help.

 

sounds to me that u need a new terastate in that sucker have u changed it latey..