2014 328TS furnace noise
First trip in colder weather and furnace used for first time. First night no problems. However, last night when the furnace is running in the bedroom/back of the rig, it started to get really noisy. Not blower noise, it sounds slightly high pitch humming. Checked the vents, no obstructions, good flow with hot air. Can't really tell where the noise was coming from.
I'm not sure where to start looking. Where is motor? Didn't go outside but will this morning. Will check outside and listen for noise. Any help? Front furnace doesn't seem to be making the noise.