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

LinkBack Thread Tools Display Modes
Old 05-08-2000, 10:46 PM
Coming back from burnout
Join Date: Jun 1999
Location: in the Pacific Northwest
Posts: 2,274
I spent the last few days overhauling my system for 134. I replaced the reciever and compressor and flushed everything.
I tried charging from the low side, but made better progress from lo/hi side. What is technically correct? The compressor didnt fire until the fifth can, when I ran a 12 volt wire to the blue white lead.
The system worked like it should. The auxiliary cooling fan came on (in front of the radiator) and conditioned air came out of the vents.
So now I hand fire my compressor with a switch in the passenger compartment.
Is there a pressure switch in the system--why doesnt the compressor get its signal normally? If so, will I have to evacuate the sytem to install a new pressure switch?
Please remember 50% of the fun on these cars is solving the technical riddles.The other half is pulling up to the dealer to buy parts and watching people pick up thier cars at service.

Reply With Quote
Old 05-09-2000, 07:51 AM
Join Date: Mar 2000
Location: Gainesville FL
Posts: 6,844
"Please remember 50% of the fun on these cars is solving the technical riddles.The other half is pulling up to the dealer to buy parts and watching people pick up thier cars at service."

You can imagine my fun then... watching DIYers play with these simple systems (vbg LOL).

The pressure switch is on the drier and should have connected the circuit with a very small ammount of pressure. The original switch was probably just a low pressure switch (for preventing the compressor from burn-out pumping a dry system). The new switch will be a low/high pressure switch which will prevent damage from over-pressure; very necessary with R134a systems.

The system will have to be discharged to remove the switch. Check the circuit at the switch to be sure its the problem. If its the problem one side will be hot (battery voltage approx) and the other side not.

Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician
Reply With Quote
Old 05-09-2000, 09:04 AM
Posts: n/a

Where can I get the different pressure switch to be used with R134, and what do I ask for.. As I recall, the switch currently installed has two leads for the fan and two for the compressor.

This would be for use with my aftermarket A/C on my 240D.

Thanks for any help,

PS. Steve, I'm sure that I speak for everyone when I say there is no need to apologize for a delayed response. We appreciated very much your sharing your vast knowledge with us. LB
Reply With Quote
Old 05-09-2000, 11:47 AM
Coming back from burnout
Join Date: Jun 1999
Location: in the Pacific Northwest
Posts: 2,274
I knew I had it coming to me even as I typed those lines!
But truthfully, I have rebuilt five or six engines, including the 240D Diesel and a Rotary. In my beginning years, I also destroyed a lot of stuff.
Usually my work is very good. I shouldnt have been cocky, but you cant blame me for feeling a sense of pride watching the well-to-do pay their service bills.
Reply With Quote
Old 05-09-2000, 10:31 PM
Registered User
Join Date: Mar 1999
Location: Suwanee, GA, USA
Posts: 4,712
On the installs where the trinary switch is needed, we are using a switch from a A/C hose rebuilder. It has a low pressure and a high pressure switch for the fan built into one. It has 3 functions.
1. Turn off the compressor if you have refrigerant loss
2. Turn off the compressor if you have and overpressure situation
3. Turn on the aux fan at over 225psi.

This will take out the old style temp regulation of the aux fan. In 134 systems, the pressure may build faster than the temp.

Donnie Drummonds
1992 500E (very soon I hope
1981 280GE SWB

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
Procedure for Replacing Neutral Safety Switch on 126 Chassis downeyjc Tech Help 2 06-20-2008 01:47 AM
Yes,another oil pressure question. mb123mercedes Diesel Discussion 8 04-28-2004 09:23 AM
Low pressure compressor cut-off switch pmizell Tech Help 4 04-20-2004 12:54 PM
WTB: Hazard Switch for an 79 240D jrmd01 Mercedes-Benz Used Parts For Sale & Wanted 4 11-15-2003 08:15 PM
Euro Light Switch Question rob_frick Diesel Discussion 4 12-29-2002 11:23 PM

All times are GMT -4. The time now is 01:09 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2022, 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