Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help

Go Back   PeachParts Mercedes ShopForum > Technical Information and Support > Tech Help

LinkBack Thread Tools Display Modes
Old 03-12-2001, 09:38 AM
Al M.
Posts: n/a
87 420 sel
Recently, My auxiliary fan comes on when I turn the ignition (the car isn't turned on yet!). I hadn't noticed this before but now it comes on and stays on through out the drive. The car hasn't been driven so its cold when I start it but the auxiliary fan still comes on. Is this something that I should be concerned with.
Reply With Quote
Old 03-12-2001, 11:52 AM
Ali Al-Chalabi's Avatar
Senior Member
Join Date: Nov 2000
Location: Knoxville, TN
Posts: 1,837
This doesn't sound normal to me.

The fan is supposed to come on high when the coolant temp gets to about 110C.

It will also cycle on and off low when the air condition is on and the refrigerant pressure reaches a certain limit.

Don't know how to fix it.
Reply With Quote
Old 03-12-2001, 02:20 PM
MBenzNL's Avatar
Join Date: Jan 2001
Location: the Netherlands
Posts: 1,417
The auxiliary fans are powered by either the airco (pressure in the airco system to high) or by the engine temperature being too high. I think that either a sensor of the airco or the motor temp is broken. The module for the auxiliary fans probably is out of one ground pulse (coming from airco or engine temp sensor), which results in the fans blowing at maximum speed...

...or something close to that...(I have no experience with the W126 S class)

1990 300SL-24
1993 C250D
with a minor 600+k kilometer
(the Netherlands)
Reply With Quote
Old 03-12-2001, 03:11 PM
Al M.
Posts: n/a
is this a very serious problem that need immediate attention? can this possibly hurt the engine, cooling system, etc...
Reply With Quote
Old 03-12-2001, 04:08 PM
Ali Al-Chalabi's Avatar
Senior Member
Join Date: Nov 2000
Location: Knoxville, TN
Posts: 1,837
It shouldn't necessarily hurt anything, it just gets really annoying and wastes a energy.

It isn't an emergency, but I would get it taken care of.

If the air conditioner is on, the fans could cycle on and off low even before the car gets a chance to reach full temp.
Reply With Quote
Old 03-12-2001, 06:12 PM
Registered User
Join Date: Jan 2001
Location: Santa Clara, CA
Posts: 437
Usually, if you slap the thermo switch when the car is cold and the power is off, the switch will reset. However, it may again stick in the "on" position when it gets hot. At that point, simply buy a new one as it isn't salvageable.
'76 240D-Sold
'78 240D-Sold
'85 300 SD, 165K-Sold
'88 300 TE, 165K-Sold
'64 Porsche 356C Cabriolet
'86 560SL 124K Miles
'94 320E Wagon, 74K Miles-128K Miles JUNKED
'06 E350 Wagon, 84K Miles
Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
Auxillary fan always on D Man Diesel Discussion 24 03-26-2006 04:14 AM
DIY Notes may help people: Radiator, Fan Clutch, Temp Sensors, Fuel Pump, Temp Gauge ericgr SL Forum 3 09-24-2004 01:40 AM
A/C - Auxillary fan problems Thomas Zellers Tech Help 2 08-29-2001 07:19 AM
Auxillary fan Kodiak Tech Help 3 08-07-2001 12:38 PM
Auxillary Fan not working on 300sd DP Diesel Discussion 2 06-25-2000 08:23 AM

All times are GMT -4. The time now is 01:51 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page