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 11-29-2001, 06:44 PM
Omega's Avatar
Registered User
Join Date: May 2001
Location: Toronto, Ontario
Posts: 25
Question Strange heat problem in W126

Hi all,
I'm having a strange heat problem in my '84 500SEL. This morning driving to work in freezing rain the heat worked great. On the way home, for the most part it worked great, however, I stopped to get gas, restarted the car put the defroster on which was blowing hot air, no problem. However, when I changed to one of the other settings cool air started blowing out of the vents even with the temp guage turned to max and no matter which blower setting. Any ideas what this could be? and what this may cost to fix. Any help would be greatly appreciated.

Mike Hudson
'84 500SEL
Reply With Quote
Old 01-04-2002, 01:04 AM
Registered User
Join Date: Sep 2001
Posts: 131
mono valve

I had a similar problem except on mine I was receiving no heat the majority of the time but every once in a while there was heat. My problem was I had a bad monovalve. The monovalve is located to the right of the battery on the engine side of the firewall. The top should have 4 screws and a electrical plug on top with a metal cylinder poking out about a half inch. Unscrew the 4 screws and unplug the electrical wire. Pull the core of the monovalve out and then pull the bottom half out. You should now have just the part the was sticking out the top (looks king of like a spark plug but larger). There should be a plunger type thing that should be able to be pulled out about 1/4 inch or so. Pull this out and check to see if there is a rubber seal that goes for the outside to the middle plunger-like thing. If this has disintegrated then that is your problem. Go to fastlane and search for the monovalve repair kit (around $35) and put the pieces that come in the box (spark-plug like thing and bumpy washer) in place of the faulty ones in the monovalve and reassemble. Now your heater should work like new.
89 300E Pearl Grey Metallic
7 Spoke 16" staggered wheels (SLK)
215/55/16 Hankook Ventus HRII H405 tires
Euro Headlights
Smoked Corners
Smoked red/clear tail lights

1987 300e Black Metallic (mom's car)
8 hole 15" wheels (C Class)
Clear Corners
Red/Smoked tail lights
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
'90 300E heat problem mikey-az Tech Help 7 03-14-2003 06:55 PM
heat problem on 1986 560 sel manorview Tech Help 1 01-15-2003 09:41 PM
Strange a/c problem on '86 300E can-do Tech Help 4 06-07-2002 12:12 AM
W126 pulls to right, not alignment problem ArizonaDAK Tech Help 4 06-04-2002 10:05 AM
Strange Throttle Problem cheech9 Tech Help 4 10-18-2001 11:45 PM

All times are GMT -4. The time now is 12:48 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