I have a 2004 F250 CCSB 6.0 diesel. The problem I'm having is that vacuum is bleeding off when the control is set to OFF or MAX A/C. I also have no vacuum at the MAX A/C level to close the heater valve. Does anyone have a vacuum schematic for an 03 or 04 truck with manual controls or can anyone tell me what the malfunction is?

 

In addition to the coolant shut-off valve, that branch circuit is also supplying vacuum to the inlet airflow vacuum motor right behind the glove box. Drop the glove box all the way open and you should see it right there.

That circuit is supposed to have vacuum in both OFF and MAX.

Trace those two lines and look for a broken hose or tee connector.

 

Thank you for the quick response sir. I actually found out I have that diagram stored away in my archives and was just getting ready to ask where that motor was. With my luck I was figuring that it was packed away against the firewall above the plenum box somewhere.