Question Details	Asked By	Asked On
Attic Fan Repair	handyman	09/28/04
I am having problems with my home attic fan that I am needing assistance with. My fan has a timer and a toggle switch to turn it to high and low. When I turn the switch on, along with the timer, the baffles will not open and the motor makes a humming sound. Sometimes when I leave the fan alone and try it again hours later the fan will work fine and come right on. Does anyone have any ideas what might be wrong with it? Does it sound like it might be the fan or could it be a bad wall switch or something like that? Does anyone have any expertise in something like this? Thanks
Clarification/Follow-up by handyman on 09/29/04 8:02 am: When you say to "short the terminals" are you meaning to just unhook the wires and hook them to the multimeter? Thanks! Clarification/Follow-up by labman on 09/29/04 5:26 pm: No. Take a screwdriver with a substantial rubber or plastic handle and contact both terminals at the same time with the blade. This discharges the capacitor protecting the meter and allowing the test to work.
Answered By		Answered On
labman		09/29/04
My guess is that the motor is failing. If it is capacitor start, it could be the capacitor. Capacitor start motors have leads running from the motor over to a small metal can. You can do a rough check on one using a multimeter. With the power off, short the terminals. A healthy one will then show a slight conductivity initially, then rapidly going to the high end of the ohm scale when the meter is connected. If the capacitor is OK, go to the switch. It should have 3 wires, 2 black ones, and another. With the power off, disconnect the switch, noting where the 2 black ones were. and connect all 3 together. Turn the power back on. The fan should start up in high. If not, likely the motor is bad. Remove it and take it to an electrical supply house and have them match it. You could also see if you can find a match at www.meci.com or www.mouser.com. If the fan runs, you can likely find a new switch at your local hardware store for a few bucks. Usually the baffles are activated by the air and not the power. Try working them by hand.

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