I own an Ultra sx 80 furnace and during the night we awoke to this screechy sound. Reminded me of either a dry pully. After a minute or so the heater came on and the noise stopped. Within another few minutes it went off and screeched again. When the heater came back on it stayed on and seemed to be working well. An hour later another small screech but didn't last long. What do you suppose is the problem?

https://servicechampions.com/scary-furnace-noises/

Screeching – Grinding, squealing or screeching noises coming from your furnace are most likely a result of problems with a bearing, belt or the motor. While this isn’t dangerous, if left it can cause larger

repairs

later.

Could be a bearing in the inducer fan, that comes on first and then the air handler.