2001 E450 SD Vacuum check valve??
Hello...I have a 2001 Ford V10 E450 running my class C and just this weekend we were driving and notice the fan for AC or Heat or vent will go from dash air to defrost when the motor is under stress l...
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On my 1999 E450 chassie a critter chewed on the plastic vacuum line at the intake manifold exit and the check valve was malfunctioning. The check valve and canister are buried behind the heater/ac on the pass side. To get at the valve you have to drain the ac and remove the components. I made it easier on mine. I rerouted the vacuum lines and repositioned the valve and canister behind the passenger lower dash panel. If you look on youtube, some guys cut a hole in the inner fender to get at the canister and valve. My method is easier.
