Forum Discussion
j-d
Jan 18, 2014Explorer II
Default for automotive Heat Vent A/C (HVAC) system output is DEFROSTER. May be hard to reach on Class A, but find a way to check and see if air is blowing out of the Defrost Vents regardless of how you set the control knob. Maybe put a couple sheets of paper up there and see if they flutter up when you turn the system on and the fan up.
The most common cause of default to defrost is vacuum failure. Vacuum line from engine to vacuum canister, canister to mode control which is actually a vacuum select "switch."
Has there been any recent work? Somebody may have disturbed or broken something.
Of course something could be wrong with that select switch, connector off it, damaged vacuum servos.
The most common cause of default to defrost is vacuum failure. Vacuum line from engine to vacuum canister, canister to mode control which is actually a vacuum select "switch."
Has there been any recent work? Somebody may have disturbed or broken something.
Of course something could be wrong with that select switch, connector off it, damaged vacuum servos.
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