OK sorry for posting another aux fan question. I did do a search and have psoted before but still no luck. herea re my questions please help.

1987 190E 2.3 78,000 miles. I have never heard the aux fans engage on this vehicle and now when I am driving I am getting funky guage readings. Most of the time it is decent, no higher than 100. But the last two days it is going higher (sometimes to the red line for a minute and then quick down to normal then back up again) and higher and nothing is engaging (aux fans). From what I have read so far it seems to either be a relay or a sensor??. Here are my questions in this model what can i do to make the fan go on, what do i pull to trigger them in the engine. Which sensor if disconnected will trigger them and also where is it? if this does not trigger it then I assume it is a relay? Where is this located in my vehicle? I looked in the fuse box and I have at th rear of it two boxes, silver and black and a space next to them that is empty? (not sure if something is missing or just an option I do not have?) From reading here I am thinking that I need a relay? I see nothing with a fuse on top of it? Ugh, thanks for everyones help. I would take it to the dealer but I have a feeling it is something easy or simple that I can diagnose myself but am having no luck) So to summarize:

1. What can i pull in the engine to trigger the fans

2. If this does not work than I can assume it is the realy hopefully? Where is it and what does it look like?

As you can see I very green when it comes to repair but it seems like I should be able to do this right? ugh, thanks