Nutone CV-350 (Central Vac) Electrical Problem


I'm having a problem with the Nutone central vac system in my house ... it will turn ON when the low voltage circuit is "made" (when the hose is plugged into an outlet) ... but sometimes it won't turn OFF when the circuit is broken by turning the switch on the handle to the off position. Tonight, I turned the unit on from the switch on the motor housing in the garage, and the only way I was able to turn it off was to unplug it. Now the motor starts back up whenever I plug it back in ... even with the switch in the OFF position, and no hose in any of the vacuum outlets!
I looked on the Nutone web site and found a parts diagram showing a "relay assembly" ... but no wiring diagram. So my question to all you knowledgeable folks ... is this relay most likely my problem? Would anyone possibly have a wiring diagram for this product?
Thanks in advance for any constructive information!
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Bankerjohn wrote:

Sounds like relay problem(sticky contacts). Low voltage controls replay which in turn applies 120V to the motor.
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Tony Hwang wrote:

Yep, it's likely the relay. You can open them up, unstick the contacts and gently clean them off with some fine siicon carbide paper. I had the same problem about 5 years ago and it's been working perfectly since cleaning.
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