the fan that cools the hot gas returning from the furnace is usally an AC voltage, capacitor start motor. based on the timing of your noise, it could be the capacitor is ready to fail. other than the noise, if your unit is working as expected, I would find the capacitor, it will be on or near the motor, there will be 2 or 3 wires connected to it and the motor and more than likely are spade clips that just slide together. **make sure your power disconnect is turned off** look for a negative/positive markings, numbers or letters, you want to reconnect the new one properly. Disconnect and take to an appliance parts store, for less than $50 will be a cheap attempt and more than likely your culprit.
May 28, 2010 Rating
check by: Anonymous
Dear Gary,
Check whether it is sound of duct(only in case of ductable unit)
May 27, 2010 Rating
Central Ac made Buzz sound by: Dadan
"After 1-3 seconds the noise stops and the blower kicks on."
So, it's not the blower that making that noise. Here to verify it. Turn your thermostat Fan from Auto to On. Does it makes that noise?
