My '89 560SL climate control/thermometer fuse keeps blowing. Help!

[sshanky]

My 89 560SL is exhibiting a weird electrical problem that I'm not sure how to solve.

I first noticed it when my climate control fan wouldn't go on. At the same time, I noticed that my thermometer was dead. I checked the white fuse, and sure enough, it was blown. I replaced it and all was well.

A few weeks later, it happened again. I knew it was the fuse, but I was concerned about what caused it. I put a new one in, and problem was fixed, this time, maybe only for a week.

It started happening more frequently, and now, when I put a new fuse it, it blows immediately when I turn the key to the on position (before starting the car). I have the fuse cover off, and I can see the spark and the blown fuse immediately when the key is turned on.

Does anyone know of some common issues that could be causing this particular fuse to blow, or how I may fix the issue?

Thanks in advance. It's hot out here in Phoenix, and I can't drive the car with the AC not blowing!