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 06-17-2001, 03:59 PM
Registered User
Join Date: Apr 2000
Posts: 75
Okay anyone have an answer for this one?

1978 W123 300D

Air conditioning blows cold air, but compressor never cycles off, nor does the aux. fan ever kick in with the A/C on. Well, actually, the aux, fan never kicks on at all at any temperature. When I first got the car, the aux. fan ran constantly, so I replaced the sensor at the thermostat. Fan stopped running constantly. If I jump the sensor at the thermostat, the fan will run.

Any ideas anyone??


Reply With Quote
Old 06-17-2001, 06:46 PM
Join Date: Mar 2000
Location: Gainesville FL
Posts: 6,844
The compressor is ultimately cycled by the ETR (evaporator temp regulator) switch. It is behind and below the glovebox, accessible by removing the lower dash panel (relatively easy to expose -right in front). Unless the temp is getting cold it will never cycle. If the A/C is functioning properly the evaporator will freeze into a block of ice within a half hour in humid climates. If it can't make it below 50deg it might never cycle and it surely won't freeze up.

The same holds for the aux fan. It is activated by an engine temp switch of 212 degrees and a thermostatic switch mounted on the drier. The early thermostatic switches had to be pretty hot before they would set it off. If your A/C system is low or working poorly the thing will never creat the heat necessary to turn the fan on.
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician
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
W123 A/C compressor knock oilburninokie Diesel Discussion 6 07-17-2004 11:29 AM
W123 A/C Spacers TonyFromWestOz Diesel Discussion 0 05-02-2004 10:13 AM
W123 A/C parts list req'd - where from?!! joeywarren Tech Help 1 08-27-2003 12:33 PM
W123 A/C Evaporator - For Sale jgl1 Mercedes Used Parts For Sale & Wanted 0 11-14-2002 10:31 AM
WTB: A/C Condenser for late W123 ncarter Mercedes Used Parts For Sale & Wanted 0 11-12-2001 05:11 PM

All times are GMT -4. The time now is 01:36 AM.

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