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

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 11-11-2013, 07:08 AM
Registered User
 
Join Date: Mar 2013
Posts: 8
1984 w123 All heat except min setting

Hi I have a 1984 300d.

I have been working to resolve this issue for quite some time now.

I get heat no matter what temperature setting is selected (except min) on the temp wheel. No modulation what so ever.

-I checked the monovalve (not torn, sees varying voltage when temperature wheel is moved)
-Replaced the foam tube for the dash temp sensor... can I test that sensor?

I would assume the temp wheel is working correctly since the voltage at the monovalve changes when moved.

Any ideas where I can go from here?

Reply With Quote
  #2  
Old 11-12-2013, 07:17 AM
Registered User
 
Join Date: Oct 2013
Posts: 52
You have no air blowing or it is not hot?

This is often a vacuum issue - may be best to post in diesel discussion group.
Reply With Quote
  #3  
Old 11-12-2013, 11:08 AM
vstech's Avatar
DD MOD, HVAC,MCP,Mac,GMAC
 
Join Date: Mar 2006
Location: Mount Holly, NC
Posts: 26,835
I'll move the thread...
__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
Reply With Quote
  #4  
Old 11-22-2013, 08:15 AM
Registered User
 
Join Date: Mar 2013
Posts: 8
Update.

I was getting full heat... Very hot, had to lower a window.

I replaced the mono-valve internals and now I get intermittent heat all hot or blowing cold air , now it's blowing cold most of the time no matter where the temp wheel is set.

Please move this thread back to the general tech page as this is not diesel specific.
Reply With Quote
  #5  
Old 11-22-2013, 08:35 AM
vstech's Avatar
DD MOD, HVAC,MCP,Mac,GMAC
 
Join Date: Mar 2006
Location: Mount Holly, NC
Posts: 26,835
however, it's 123 specific... and 99% of the 123's are Diesel.

very little knowledge available in the Tech help section (should be named GASSER help) on the 123 controls...
__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
Reply With Quote
  #6  
Old 11-22-2013, 08:45 AM
vstech's Avatar
DD MOD, HVAC,MCP,Mac,GMAC
 
Join Date: Mar 2006
Location: Mount Holly, NC
Posts: 26,835
Hmm.
do you still have the original monovalve? do a search for CCU sequence, or climate control testing... I'll see if I can find it.
you may want to pull the climate control out and check the solder joints for cracks. resoldering the joints repairs MANY CCU issues.
also, if the aux pump is bad, it can overwhelm the CCU circuit.
__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
Reply With Quote
  #7  
Old 11-22-2013, 09:22 AM
Registered User
 
Join Date: Mar 2013
Posts: 8
Thanks for the info.

Does not look like the original mono valve the wires were cut and spliced in... I soldered them yesterday.

I'll have to dive into the acc unit. Another thread mentioned the control box behind the glove box any idea how to check that if it has failed?
Reply With Quote
  #8  
Old 11-22-2013, 09:44 AM
vstech's Avatar
DD MOD, HVAC,MCP,Mac,GMAC
 
Join Date: Mar 2006
Location: Mount Holly, NC
Posts: 26,835
here is a writeup on CCU service.
PeachPartsWiki: Climate Control Repair
__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
Reply With Quote
  #9  
Old 11-22-2013, 10:06 AM
Registered User
 
Join Date: Oct 2007
Location: St. Thomas PA
Posts: 957
Remove the glove compartment and verify that the vacuum tube that aspirates the temp. sensor in the dash is still connected. They tend to deteriorate over time.
__________________
'83 300D, 126K miles.
Reply With Quote
  #10  
Old 11-22-2013, 01:34 PM
Registered User
 
Join Date: Mar 2013
Posts: 8
I replaced the foam tube for the dash sensor last year. How can I test the interior temp sensor is operating correctly?
Reply With Quote
  #11  
Old 11-22-2013, 01:38 PM
fashion victim immunizer
 
Join Date: Feb 2012
Location: oakland
Posts: 930
i had this problem and replacing the unit behind the glove box fixed it.

__________________
1981 NA 300D 310k miles
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 08:19 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page