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Re: benchtesting air control valve?[200/1981] posted by Don Foster on
Saturday, 4 August 2001, at 1:05 p.m.
"...imagine these get gummed up and sticky..."
Indeed they do.
A good test is measuring resistance from the center pin to each end pin (in the 3-pin connector) while carefully and slowly rotating the armature from one stop to the other. This is best done with a Q-tip to avoid scratching the valve armature.
The resistance should be around 25 ohms, more or less. Over 200 ohms indicates that the brushes and/or commutator are burned. In particular, watch for a dead spot (very high or infinite resistance). It's this dead spot that causes the motors to freeze in one location, and it's the problem you can temporarily overcome by whacking the CIS motor with a hammer.
Be aware that when you turn the armature it generates a tiny current -- this will drive the ohmmeter nuts, so patience (and a leisurely approach) is required while evaluation the motor.
Don Foster (near Cape Cod, MA)