This was in another thread that I created, but this is a more detailed post with more information.
Background: I just moved into a new house with a Trane XE90 gas furnace. Combustion air is from inside the house (No air intake that I can see) and the blower works fine after it starts. No combustion issues either. This happens with a filter in or out, so it is not a ductwork issue.
So about 3 weeks ago I noticed that I am now getting a 1 second clunk (or rumble) when the blower clicks on in my XE90 furnace. I took the cover off and held in the safety switch to see where the noise was coming from. It doesnt appear to be coming from the blower motor itself, however it does seem to be coming from the area of the 2 silver colored cylinders (might be just one unit oval in shape) attached to the side of the blower housing (I think each has a red wire going from it to the motor and they both have a silver cover or "strap" over them). Is that the start/run capacitors, and if so could they be making that noise?
I noticed this started when I tried to keep my fan turned 'ON' from the thermostat. It started making this noise about every 20-30 minutes on a regular basis. Could the old POS thermostat have kept sending a start up signal (noticed that with the fan in 'AUTO' it would click on at about the same interval) and therefore damaged the capacitors?
If this is the issue, where can I buy these capacitors, and how hard are they to replace (do I have to discharge them before I unhook them, and if so how do I do that)?
Also, does the blower motor have to be oiled at all for maintenance?