Maybe the sail switch
I had same symptoms. Fan for a while then nothing. There is a switch that detects that the fan is working. Called a sail switch. On my unit it is easy to access with the exterior panel removed. It is screwed to the fan housing right in front. Easy to check with a meter if itís working. In my case I removed the switch, checked it with a meter, it checked ok, then I put it back in and all is well. I think it had stuck in the on position which is a no go for the furnace logic. I ordered a new one and it lives in my tool box as a back up.