Yes. That's the screw in fuse.

To be clear your furnace fan doesn't come on? I am referring to the furnace. Not the condenser.

The sight glass should be on the non louvered panel of the furnace. Otherwise pull this panel and hold or block the door switch and look at the main board for a few minutes while you've got it set to run. That panel should have a trouble code diagram on the back of it.