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 > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 01-23-2010, 02:09 PM
Registered User
 
Join Date: Sep 2008
Posts: 47
No heat with evil servo

I have not been able to get heat in my 1980 300sd with the dreaded evil servo setup. The original servo in the car was not working, severely cracked and plugged up with crud. I recently replaced it with a nice used aluminum unit. The motor in the new servo seems to work because I can hear it running after I shut the car off. I also replaced the amplifier with a rebuilt unit and put in a new auxilliary water pump which is working. When I push the defrost button, the blower comes on but I get no heat. When I push auto lo or auto high, the blower will not come on at all. So i have two questions. Number one, why am I not getting any heat in defrost? Number two, why will the blower not even come on in the auto lo or auto high positions?
Reply With Quote
  #2  
Old 01-23-2010, 02:16 PM
Registered User
 
Join Date: Jan 2002
Posts: 18,355
It works in the defrost position because that is the default for the system. I linked the manual for the evil servo system in a post here so if you search on my username and servo manual, you'll find a link.
There is a central vacuum control switch which has to be activated for the system to function but if your blower is working, I believe that switch is functional. On my W116 there appears to be a second main switch next to the main vacuum switch. I've never looked into it far enough to determine what that switch controls but maybe it's not working correctly. On the W116 the vacuum control switch and the other switch are behind the glovebox.
__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
Reply With Quote
  #3  
Old 01-23-2010, 05:12 PM
whunter's Avatar
Moderator
 
Join Date: Dec 2003
Location: Metro Detroit, Michigan
Posts: 17,352
Answer

Quote:
Originally Posted by KJenkins View Post
I have not been able to get heat in my 1980 300sd with the dreaded evil servo setup. The original servo in the car was not working, severely cracked and plugged up with crud. I recently replaced it with a nice used aluminum unit. The motor in the new servo seems to work because I can hear it running after I shut the car off. I also replaced the amplifier with a rebuilt unit and put in a new auxilliary water pump which is working. When I push the defrost button, the blower comes on but I get no heat. When I push auto lo or auto high, the blower will not come on at all. So i have two questions. Number one, why am I not getting any heat in defrost? Number two, why will the blower not even come on in the auto lo or auto high positions?
Servo service manual
http://www.peachparts.com/shopforum/general-information/240606-evil-servo-service-manual.html#post2053754


http://www.imperialclub.com/Repair/Lit/Master/281/cover.htm









Have a great day.
__________________
ASE Master Mechanic
asemastermechanic@juno.com

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Prototype Vehicle build.
Prototype Fleet Durability
Prototype vehicle instrumentation.
Technical Quality Auditor.
Automotive Technical Writer

1973 300D
1973 309D - stolen
1978 280SE
1980 240D
1983 300D
1984 190D
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




All times are GMT -4. The time now is 09:42 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