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!

[560sl4me]

My suggestion is to check the outside temperature sensor and wiring
located center of front bumper, behind license plate bracket.

[sshanky]

Thanks for the suggestion. I removed the license plate bracket, and found the sensor. I followed the wire back (without removing it) to the rubber grommet that leads into the glove box. I removed the glove box liner and tried to find where that wire leads, but it was difficult to get to alone, so I decided to wait until my friend can help me. Meanwhile, the cable appeared to be in good condition (where I could see it). Is there an easy way to unplug the sensor somewhere inside the dash where I can access it through the glove box opening, so I can see if this is the culprit? Any other tests I could try?

Thanks

[560sl4me]

You might want to disconnect the temperature senor and check for
resistance using an ohm meter.

Resistance at 20 degree centigrade nominal 363 ohms
max. 388 "
min. 337 "

[sshanky]

That's a good idea. Can anyone tell me where the disconnection point is? I have the glove box out and would like to find the plug at the end of the temp. sensor line. Thanks!

[560sl4me]

The senor disconnects at the front in back of the license plate bracket.

[sshanky]

Thanks...do you know where the other end of that line leads? I am worried that the short may be in the line somewhere, in the hood. I will first try disconnecting behind the license plate. Thanks again