Why does my 92 Ford Chateau club wagon AC blows through the defroster vents?

Asked by mbreat Oct 05, 2011 at 03:31 PM about the 1992 Ford E-Series E-350 Chateau Club Wagon Passenger Van Ext

Question type: Maintenance & Repair

I tracked the vacuum lines to the vacuum actuator that changes the air flow from dash vents to the defroster and found no problems. When I accelerate the vacuum drops causing the actuator to redirect air flow to the defroster vents the dash vents. I'm assuming that there is a vacuum leak up stream from the dash switch/selector but can not find the source of the leak. Any help is appreciated.

papa answered 13 years ago

under hood on driver side is a check valve,round plastic part the vac lines hook to is bad,can get at any auto parts store in the help section.

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mbreat answered 13 years ago

Thanks, couldn't find any check valve under hood on Driver's side. I checked all hoses from the intake manifold (source) to the vacuum reservoir and found no check valves nor leaks in the system. I added a check valve to the vacuum actuator for the a/c / defroster door. It seemed to help some but I still loose vacuum when accelerating even with the check valve added. I have seen technicians add smoke to the intake system to check for leaks. Where might I find this "smoke"?

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papa answered 13 years ago

is at firewall at break booster,close to inner finderwell.is 3 vac lines hooked to it.

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