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Marty
Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 53157
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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How can I make my auxiliary fans stop turning or shut off

Customer Question

How can I make my auxiliary fans stop turning or shut off after engine has been turned off?
Submitted: 1 year ago.
Category: Mercedes
Expert:  Marty replied 1 year ago.

Hi, what year and model is your Mercedes?

Customer: replied 1 year ago.
Marty, this is a 1992 500SEL -
Expert:  Marty replied 1 year ago.

Ok, are the fans running continuously with the key off?

Customer: replied 1 year ago.
Marty, I placed all of this information in the details of the original question.
You are correct - when the engine is off, nothing ON, AC off, doors locked and I got to sleep, the fan continue to run.
When I take out the fuse/relay out, they go out, when I unplug them at the fan connection (in front) each fan turns off.
They come back on, regardless of what the temperature inside, outside, in the car or air is - this causes the battery to deplete and we got stuck Friday night at 3:00 AM in a parking garage, needing a jump to get the car started. I hope this helps.
Customer: replied 1 year ago.
it looks like somehow, they have affected the horns too - both horns do not work - the alarm arm works, but not the two in the front of the bumper (left and right - Low and high tones - I think they are also called the fanfare horns, the fuse is fine - not sure if there is a relay and or where it is located).
Expert:  Marty replied 1 year ago.

If you remove fuse 18 do the fans turn off?

Customer: replied 1 year ago.
No, they are still on after removing fuse 18
Expert:  Marty replied 1 year ago.

Try removing the relays at position E, F & G in the back section of the fuse box and see which one turns the fan off. It sounds like one of the relays is stuck closed. I've attached a diagram below.

Customer: replied 1 year ago.
Marty, I do not see the diagram - try again please. There is a black box (kind of rectangular) with some wires going into it -- is that a box of relays? Please don't forget to send the diagram - thanks
Expert:  Marty replied 1 year ago.

Sorry about that. Click on the diagram below. You will need to remove the lid on the fuse box to access the relays in the back of the box.

Customer: replied 1 year ago.
Marty, I don't believe the relays are located there -- I will have to send you a picture of my car - The fuse box cover when removed, does not reveal any relays -- all fuses and larger fuse types 1 - 6 I believe. A picture will help you guide me further -
Thanks
Expert:  Marty replied 1 year ago.

You did not remove enough of the cover. You need to remove the 6 or so screws that are holding the lid to the top of the box in order to access the relays in the back of the box.

Customer: replied 1 year ago.
Marty,The fan stopped running a while ago on its own - perhaps when I started to remove fuses and tried to reset /start and stop the engine with and without the fuse in and it may have un-stuck the relay as a result if it was stuck --- so the fans operate as they should -- However, I have the picture of the fuse box and for future reference, do you mean the six golden screws in this picture and by removing them, the fuses will flip up and reveal the relays? Please advise - thanks ok, for some reason I can't add files to send you the picture of the fuse box I tool for verification.
Expert:  Marty replied 1 year ago.

You have to remove the relay that mounts to the top of the box behind the fuses then remove the six screws around the perimeter of the lid and the lid will lift off leaving the fuses in place and the relays exposed. I've attached a picture below. I'd go ahead and replace the fan relays.

Expert:  Marty replied 1 year ago.

Disregard the reference to the K17 relay. You will want to replace the K9 relays.

Customer: replied 1 year ago.
ok - my car does not have those extra relays with the fuses -- please provide me with an email address so that I can send you the picture I have -- the fuses are in a box (fuses small and large) and does not look like the pic you have shared.Thanks
Expert:  Marty replied 12 months ago.

The website restricts me from sharing my private email without an additional service agreement. I've sent the agreement with this reply. You can contact customer service and send them the pictures and have them forward them to me if you prefer.