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1979 Mark V AC Servo Vacuum Motor Questions

Hi Bill -

Purchased a plastic manifold from you, trying to solve hot water valve issue, long and short of it , I believe my problem is the the vacuum motor, it will not pull the little cable back far enough to let vacuum out of the manifold to the green black hose. Tested with another vacuum connected and it does what it is supposed to do. Big question how to remove vac motor (easily ??)



Hi Kenny -

If the system pulls that servo vacuum motor only with another source of vacuum, the servo may be o/k but the Climate Control Sensor may not be sending enough vacuum to the servo. What can cause this? The possibilities are......The ambient temperature is too cold and the system cannot and will not drive to the full cooling position enough to operate the water valve and recirc. door motors even if the control selector is adjusted to 65 degrees.......The ATC Sniffer Sensor above the glove box liner could be faulty or maladjusted.......or the ATC system may not be receiving enough engine vacuum because of a vacuum leak. To remove those servo assemblies along with the plastic manifold can be tricky therefore consider the above possibilities before trying to remove it as it may not be the problem.

If you have the factory shop manual the adjustment for this sniffer sensor is shown in the climate control section. They are a well known fail item. We use a hand held vacuum pump to test these control systems.