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 10-03-2003, 05:33 PM
RMF RMF is offline
Registered User
 
Join Date: Aug 2003
Location: Denver
Posts: 12
124 climate control unit and auxiliary water pump

I have been having trouble with the climate control system and was advised to check the auxiliary water pump. Not having time to do so right away, I just disconnected the wire to the pump. Still have problem, but the heat/cooling still worked. I thought that if the pump was disconnected that there would be not much heated water coming into the heater coil, but there seems to be plenty. Is there another one of this little suckers in the system? If not, why bother keeping the pump active, especially when it can damage the CCU?

As for the overall problem, until the car is driven several miles, the outside air exchange keeps cycling off and on. Can hear clicking like a relay going on and off in the dash on the passenger side. Any thoughts on what this is other than replacing the whole climate control unit?

Any thoughts appreciated - RMF
Reply With Quote
  #2  
Old 10-03-2003, 10:23 PM
Registered User
 
Join Date: Jul 2003
Location: Montreal, Quebec
Posts: 508
The auxiliary water pump is necessary to keep the water flowing throgh the heater radiator when the engine is at idle.
If you're stucked in traffic (idle) for a certain period of time, the engine water pump does not generate enough circulation to feed the heater radiator. After a while, the coolant cools-off in the heater and you have no more heat.
jack
Reply With Quote
  #3  
Old 10-03-2003, 10:26 PM
pesuazo's Avatar
Registered User
 
Join Date: Oct 2002
Location: Near Raleigh, NC
Posts: 580
The auxiliary water pump is there to help in the circulation of the coolant when the engine is at idle. The only thing that can stop hot coolant into the cabin is by using the temperature dial, which controls (I believe) the monovalve. Once the car is running the auxiliary pump is not needed.
What you hear clicking is a malfunction of the CCU circuit board itself.
Here is the remedy:
Take the CCU out, and resolder the contact points (most likely the push buttons).
Look closely for cracks at the solder points (cold solder). Very often with age they come apart, causing the intermittent switching on and off of the fan, and the ac compresor.
I am sure that is your problem. I had the same symptons over a year ago.
__________________
1999 Porsche 996 Carrera Convertible
1994 420E - SOLD
1986 300E - SOLD, what a car
609 Certified
Reply With Quote
  #4  
Old 10-03-2003, 10:27 PM
pesuazo's Avatar
Registered User
 
Join Date: Oct 2002
Location: Near Raleigh, NC
Posts: 580
I see Jackd replied as I was typing.
__________________
1999 Porsche 996 Carrera Convertible
1994 420E - SOLD
1986 300E - SOLD, what a car
609 Certified
Reply With Quote
  #5  
Old 10-05-2003, 06:14 PM
RMF RMF is offline
Registered User
 
Join Date: Aug 2003
Location: Denver
Posts: 12
Thank you Pesuazo and Jackd. I'll take a look at the connections.
Reply With Quote
  #6  
Old 10-07-2003, 03:12 PM
RMF RMF is offline
Registered User
 
Join Date: Aug 2003
Location: Denver
Posts: 12
OK guys - I got the unit out and the bottom removed. All I see is a green circuit board with a bunch of solder joints. None appear to be cracked. Do I remove the board and look further? I have done this in the past and all looked OK. I looked at the actual wire connectors to which the switches attach, but they look in order.

Oh for the days of mechanical controls like the old 75 I have. A lot good all this gadgetry does if it does not work. I do not find it hard to reach over and move a slide lever to adjust the heat or AC.

Has anyone you know of been able to bypass all the electronics and just have basic adjustments?

RMF
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 08:18 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