I've got a basic 12 oscillating fan. Had it for about 6 months. I've noticed that if it's been off for awhile and then I turn it on, it will start really really slowly. I can hear a slight hum and I can see the blades turning veeeery slowly. If I leave it on and wait 2-5 minutes the fan will just suddenly start working properly. This only seems to happen when the fan has been off for awhile. If it's working normally and I turn it off and then on it will start without problems.Does anyone know what's going on with it? Is the motor dying? Is it clogged with dust?
Many AC motors have a capacitor that is used to start the motor and then is switched off after it reaches top speed. It is not designed to stay in the circuit for extended time. You should always start a fan on High and after it's up to speed, switch to Med or Low. If you've been starting in on Med or Low and skipped past the High setting, you never switched out the capacitor and it's probably dead now. Your description is very typical for this kind of problem. If you read the directions (who reads them for a fan?!?), you'd probably see that they wanted you to start in High and then switch to a lower speed. It probably isn't worth repairing, but it is worth remembering to always turn it on High before reducing the speed to what you want when you get your next fan.
There may be a large amount of dust inside the motor keeping the shaft from spinning freely. It also may be that the motor does have a problem. Is the humming noise much louder than normal? Usually this is a sign the motor is failing. Note that when the blades are spinning slowly, there is a chance the motor could overheat and possibly catch fire. Just to be on the safe side I would replace the fan. It also could be a problem with the oscillating mechanism. The fan motor also powers the oscillating mechanism. This mechanism could be bound up keeping the motor from spinning at its normal speed. Usually there is a knob or lever that disengages the oscillating feature. Try disengaging this and see if the problem goes away.
It could well be clogged with crud. Try spinning the blades by hand before you turn it on and see if that helps. If so, you can spray a cleaner (electronic cleaners or isopropol alcohol) into the motor housing and then let it run awhile.
