1998 BMW 323 Heater/air blower stopped working

Noticed heater/air blower drop in rpm's a couple of times as though there was low amperage or voltage. Later the blower fan stopped all together. Came back on once when I started veh then quit. Digital light bar on control panel indicates fan on.
Question would this likely be the fan motor or some kind of resistor or climate control feature failure. Is there any way to test for failed item?

The "air" conditioning compressor comes on when button is pushed but of course no blower for air.