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

LinkBack Thread Tools Display Modes
Old 06-05-2008, 02:00 PM
Registered User
Join Date: Nov 2007
Location: Texas
Posts: 16
A/C compressor wiring

Hello all,
Could someone tell me which wires going to the a/c compressor are for the low speed and for high speed. There are 4 in all.
I'm trying to diag no signal to the compressor and would like to run a toggle switch for the mean time.
I know I'm bypassing wot switch and many others but this is only temporary. It's really HOT in Texas. Also who has the best sevice manual for this 90' 300D.
Thanks very much!

Reply With Quote
Old 06-05-2008, 02:03 PM
Registered User
Join Date: Oct 2005
Posts: 4,263
The compressor has no high-speed or low-speed. You probably have two wires for the clutch coil and two wires for a speed sensor.
Reply With Quote
Old 06-05-2008, 02:42 PM
Registered User
Join Date: Nov 2007
Location: Texas
Posts: 16
ok thanks, I got the "two speed" wording from an retired mech who looked up some info for me on his all data. This system is still R12 and I initially took the car to him because I don't have R12 gauges, can't buy the freon and hoping it was just low on refrigerant.
I thought it seemed odd, the two spd. The system is full and will work if you exite the compressor but I still don't know why we aren't getting juice to the comp. via the control panel.
I'll search more for wiring diagrams online untill I get a manual. Thanks.
Reply With Quote
Old 06-05-2008, 06:15 PM
sixto's Avatar
smoke gets in your eyes
Join Date: Jun 2000
Location: SF Bay Area
Posts: 20,799
ac still not working after ac conversion 87 300SDL

87 300D
Reply With Quote
Old 06-05-2008, 06:41 PM
compress ignite's Avatar
Drone aspiring to Serfdom
Join Date: Feb 2004
Location: 32(degrees) North by 81(degrees) West
Posts: 5,554

There are three wires to the A/c compressor area.
Two for a speed sensor coil circuit(The dreaded KLIMA relay compares compressor speed to engine speed...too big a difference NO A/C.)
One to provide Positive power to the compressor clutch for engagement.

The link provided by SIXTO provides logical diagnostic steps.

#1. is blow up of compressor wires
#s 2+3 are a split of the complete schematic

Any one of the information sources (sensors,switches[gremlins]) can cause
the A/C control N6 to deny compressor engagement.
Much of this Folderol is to protect the belt that drives all the accessories.
(Think like a Mercedes engineer...No Belt...No Water Pump...Engine Overheat
Head Crack...No Fraulein in Leather Lederhosen for the Engineer.)
Attached Thumbnails
A/C compressor wiring-screenhunter_01-jun.-05-18.44.gif   A/C compressor wiring-screenhunter_03-jun.-05-18.47.gif   A/C compressor wiring-screenhunter_04-jun.-05-18.48.gif  

'84 300SD sold

Last edited by compress ignite; 06-05-2008 at 07:12 PM.
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

All times are GMT -4. The time now is 03:12 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, 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