It's that time of year ... Another AC issue

Hello folks.

Have a 2005 9200 and I hope someone can put me on track to fixing it. First, I had an issue with the dash controls. One of the knobs had broken internally. A little hot glue cured it for a time. I ordered another used unit anyway.

But now, the fan only blows on 4 (high) and then it just works in pulses until the fuse blows.

What do you think? Bad relay? Or that thingamajiggy down by the blower (can't think of what it's called as if you couldn't tell) that everyone says to replace when the fan motor goes. Which I didn't do when I changed the motor 2 months ago.

Any help is much appreciated.

 

Blower is 2 months new. Hope it ain't bad. Will look for a short and replace resistor and the relay. If those aren't the problem, I guess another blower motor is in store.