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

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 02-18-2003, 07:03 PM
BWatson's Avatar
Registered User
 
Join Date: Jan 2002
Location: Los Angeles
Posts: 222
Climate Control help?

I'm having a hard time figuring out the problem. Here are the symptoms. Heat only, no matter what setting the wheel is on. The airflow does, however, redirect up to the center vents when I move the wheel to cool but the air stays hot. I already tried a monovalve repair kit to no avail. Could it be the electric portion of the monovalve that is not working? If the climate control unit was bad, would it still do all of the other functions properly? I don't have the tools or proper information to go through th whole system but If anyone has any ideas before I take it in to my mechanic, I would be very thankful.

Looking for an easy way out!
__________________
1982 300D Turbo "Helga"
380,000 miles
Reply With Quote
  #2  
Old 02-18-2003, 07:41 PM
sixto's Avatar
smoke gets in your eyes
 
Join Date: Jun 2000
Location: SF Bay Area
Posts: 19,739
Sounds like the monovalve isn't getting any power. The default setting is full heat.

When the system is modulating heat, I believe there's a pulsed ground signal to the monovalve. The other wire is constant 12V in run or start.

Could be as complex as a bad temperature control module or as simple as a bad connection between the control module and the monovalve.

Don't discount the push button unit as the temp controller signal goes through the push button unit to be ignored (for full heat) if defrost mode is selected. But I believe there's a mechanical link between the vent selector and the monovalve mode selector inside the push button unit.

Actually, it could be as simple as a fuse but on a 126 (that's all I'm familiar with) the same fuse powers the push button unit and the monovalve.

Sixto
91 300SE
87 300SDL
83 300SD
Reply With Quote
  #3  
Old 02-19-2003, 05:13 PM
BWatson's Avatar
Registered User
 
Join Date: Jan 2002
Location: Los Angeles
Posts: 222
Thank you for the response! One more question...Where is the temperature control module? I havent looked all that hard for it but I did take off the passengers side under dash panel and I couldn't see it under there.
__________________
1982 300D Turbo "Helga"
380,000 miles
Reply With Quote
  #4  
Old 02-19-2003, 05:29 PM
jhal's Avatar
Registered User
 
Join Date: Dec 2002
Location: Brooksville Fl
Posts: 226
The temperature control module is (at least on my '85 300d) is about the glove box, mounted on a bracket. The silver box controls the temperature, the black one controls the blower.
Reply With Quote
  #5  
Old 02-19-2003, 05:43 PM
BWatson's Avatar
Registered User
 
Join Date: Jan 2002
Location: Los Angeles
Posts: 222
Aha! Thank you! Boy I hope thats not it. Quite a pricey item. Can it be repaired, resoldered, or perhaps even bypassed?
__________________
1982 300D Turbo "Helga"
380,000 miles
Reply With Quote
  #6  
Old 02-19-2003, 06:29 PM
sixto's Avatar
smoke gets in your eyes
 
Join Date: Jun 2000
Location: SF Bay Area
Posts: 19,739
The temperature controller is the heart of the ACC system. It decides when the AC compressor should be on, how much to flow through the monovalve and how strong the blower should blow. The push button unit is just a user interface.

Bypassing means moving over most of the AC innards from a 240D.

Make sure you're getting +12V to one of the monovalve terminals before tearing into the temperature controller.

Sixto
91 300SE
87 300SDL
83 300SD
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 01:48 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2011 Pelican Parts - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page