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-Benz Forum > Mercedes-Benz Tech Information and Support > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 02-07-2005, 01:49 PM
Registered User
 
Join Date: Jun 2002
Location: Monrovia, CA
Posts: 496
86 300E Aux Fan Resistor Question

Just curious - on my 86 300E should my aux. fan run at different speeds depending on whether or not the a/c is on? It seems to run at one constant (max) speed whenever it's on, whether from the a/c or just mild overheating. Isn't the resistor supposed to make it run slower under some conditions? The resistor visually appears intact and the connections are corrosion free. Is there an easy way to accurately test it? (it's sort of buried under the ABS unit, so a little hard to reach) I've done a search and didn't really find an answer for this.

Thanks for any help.

Reply With Quote
  #2  
Old 02-07-2005, 02:04 PM
Registered User
 
Join Date: Aug 1999
Location: Florida / N.H.
Posts: 8,804
Jumper the a/c high pressure switch at the reciever/drier... that will energize the low speed fan [ using the resistor.]
High fan [ no resistor]is only when coolant temps are above 105C and has nothing to do with low fan... the two just share the same fan motor, but completely different circuits/relays/sensor/fuses...
Reply With Quote
  #3  
Old 02-07-2005, 02:34 PM
Registered User
 
Join Date: Jun 2002
Location: Monrovia, CA
Posts: 496
Thanks for the reply.

Should the speed differential be quite obvious, because I can't say I've ever noticed a difference. Is there an easy way to jumper the hi-speed fan circuit to test it as well?
Reply With Quote
  #4  
Old 02-07-2005, 03:03 PM
Ta ra ra boom de ay
 
Join Date: Jun 2004
Location: Pittsburgh
Posts: 1,915
Quote:
Originally Posted by Phalcon51
Thanks for the reply.

Should the speed differential be quite obvious, because I can't say I've ever noticed a difference. Is there an easy way to jumper the hi-speed fan circuit to test it as well?
I am thinking the varable speeds came on later models, and an 86' has one speed only?
__________________
-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/showpost.php?p=831799&postcount=13
http://www.peachparts.com/shopforum/showpost.php?p=831807&postcount=14
Reply With Quote
  #5  
Old 02-07-2005, 03:38 PM
Registered User
 
Join Date: Aug 1999
Location: Florida / N.H.
Posts: 8,804
< __________________
>>

OK .
If there is a dropping resistor , it is b/c there are two fan speeds .

The high will be jumpering the 105C coolant sw..
Reply With Quote
  #6  
Old 02-07-2005, 04:56 PM
Registered User
 
Join Date: Jun 2002
Location: Monrovia, CA
Posts: 496
Quote:
Originally Posted by Arthur Dalton
If there is a dropping resistor , it is b/c there are two fan speeds .

The high will be jumpering the 105C coolant sw..
Thanks, I was thinking the same thing about the resistor. Can you tell me where the 105C switch is located, or what color wires it uses?
Reply With Quote
  #7  
Old 02-07-2005, 05:21 PM
Ta ra ra boom de ay
 
Join Date: Jun 2004
Location: Pittsburgh
Posts: 1,915
Quote:
Originally Posted by Phalcon51
Thanks, I was thinking the same thing about the resistor. Can you tell me where the 105C switch is located, or what color wires it uses?
Think you mean this one on top of valve cover (partly obstructed by air cleaner)
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1FX0MB1RS1G1117TI8&year=1986&make=MB&model=300-E-002&category=G&part=Engine+Temp.+Sensor
Here is a helpfull .pdf 4.1 megs:http://home.comcast.net/~martin.carney/1986.pdf Starts talking about your concern on pp A22 Arthur's point made on pp 23.
My AC has never worked on this car so I am somewhat unfamilar with proper operation.
__________________
-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/showpost.php?p=831799&postcount=13
http://www.peachparts.com/shopforum/showpost.php?p=831807&postcount=14

Last edited by A264172; 02-07-2005 at 06:04 PM.
Reply With Quote
  #8  
Old 02-07-2005, 06:34 PM
Registered User
 
Join Date: Aug 1999
Location: Florida / N.H.
Posts: 8,804
Quote:
Originally Posted by Phalcon51
Thanks, I was thinking the same thing about the resistor. Can you tell me where the 105C switch is located, or what color wires it uses?

The 105/115 switch [S-25/6] is on top of engine . The wire you want to ground for high fan activation is br/gn. That will complete the circuit from K9 high speed aux. fan relay , which by-passes the dropping resistor and feed fan motor full 12v.

For low fan, you jumper br/bu and br at reciever/drier switch [ S/32 } for low fan relay K-10 preresistor circuit. This feed uses the resistor in series to drop the feed voltage to fan ,resulting in low fan mode [ a/c only]

Reply With Quote
Reply

Bookmarks

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
M119 Viscous Fan mod & problems with aux. fan resistor-mod ke6dcj Mercedes-Benz Performance Paddock 92 05-19-2010 10:36 AM
Help Please!!! Aux. fan wouldn't shut off ilinaksita Tech Help 3 05-27-2003 10:22 AM
Noisy Aux fan on 96 E320 mb96 Tech Help 2 09-16-2002 03:35 PM
aux fan blues JHZR2 Diesel Discussion 5 07-14-2002 03:49 PM
Aux. Fan advice requested. darius Tech Help 2 05-08-2000 10:03 AM



All times are GMT -4. The time now is 01:19 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page