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

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 08-21-2005, 09:33 PM
Eiknujrac's Avatar
Car Junkie
 
Join Date: Oct 2003
Posts: 99
Thump/Water Drop sound from Dash w202

1998 C280

So when I pulled up to a stoplight the other day, I noticed my AC system was making a really strange noise. About every 3-4 seconds, there will be a thump noise, which is loud enough to be felt through the dash by my knee, and most of the time, this thump is accompanied by a water droplet sound. The AC seems to be working fine, blowing fast and cold. But this sound is very annoying when I want a quiet ride home.

Anyone ever have this noise before? or have any idea what it is?

Thanks in advance.

__________________
I love my cars to death but my wallet sure doesn't.
Reply With Quote
  #2  
Old 08-22-2005, 04:09 PM
Eiknujrac's Avatar
Car Junkie
 
Join Date: Oct 2003
Posts: 99
UPDATE: found that the sound only occurs with the AC on, no sound with the heat on. Anyone?
__________________
I love my cars to death but my wallet sure doesn't.
Reply With Quote
  #3  
Old 08-22-2005, 04:15 PM
Craig
Guest
 
Posts: n/a
Just a guess, but is you AC drain plugged? I'm not sure about the thump, but it seems that water may be building up, then draining all at once.
Reply With Quote
  #4  
Old 08-22-2005, 04:20 PM
michakaveli's Avatar
Registered User
 
Join Date: Nov 2002
Location: Columbia, SC
Posts: 1,719
Our '96 C220 also has the loud THUMP, it occurs at all times that the blower is working, AC on or off - although there is no water drop sound to follow. It driver me up the wall, but since everything works fine I have just left it alone.
__________________
#dieselFLEET
---------------
'97 E300
'99 E300
Reply With Quote
  #5  
Old 08-22-2005, 04:29 PM
Registered User
 
Join Date: Feb 2002
Location: east coast
Posts: 1,255
there have been other post about the thump, also check where I think it is also discussed.

The thump is from the auxillary water pump or maybe an item called the duo-valve that is activated by the climate control.

I have always been able to sense that thump in my car, but cannot say I flet it through the dash by my knee.

Oddly enough for the first time in 77K miles I got a similar dripping noise, as a test I ran my HVAC with the EC light on, fan speed at maximum, and temp on the hottest, also adjusted vents to downward airflow icon on the HVAC unit. I ran it that way while driving for around ten minutes. The dripping sound went away.
Reply With Quote
  #6  
Old 08-22-2005, 05:14 PM
benzfan's Avatar
Registered User
 
Join Date: May 2001
Location: Toronto
Posts: 277
The sound is indeed the duovalve. It cycles at a rate depending on the need for heating in the heater core. With the A/C on, the duovalve will still be required to help maintain the core temperature. In the spring and fall, when minimal heating is required in the cabin, you will hear the valve cycling more. Both of my 202s do it. The gurgling is the water being let through the heater core a small slug at a time as the valve cycles. I recall posting a lengthy reply on this subject to someone on club202.com.
__________________
'96 C280 (gone)
'97 C36
'05 C230k
Reply With Quote
  #7  
Old 08-22-2005, 06:41 PM
Eiknujrac's Avatar
Car Junkie
 
Join Date: Oct 2003
Posts: 99
Thanks alot for the replies guys.

But just to clear things up, this is a normal sound right? And even the newer valves make the same noise?
__________________
I love my cars to death but my wallet sure doesn't.
Reply With Quote
  #8  
Old 08-22-2005, 07:37 PM
Registered User
 
Join Date: Feb 2002
Location: east coast
Posts: 1,255
the thunp is normal

the drip sound I am not so sure, but try what I described and hopefully the drip sound will stop
Reply With Quote
  #9  
Old 08-22-2005, 09:32 PM
Eiknujrac's Avatar
Car Junkie
 
Join Date: Oct 2003
Posts: 99
Thanks guys, I really appreciate it.

I'll try the drip thing tommorow and post an update.

__________________
I love my cars to death but my wallet sure doesn't.
Reply With Quote
Reply

Bookmarks


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
Water gurgling sound in dash EricH Tech Help 7 12-19-2002 01:27 PM
Annoying click click sound from dash (W210) aTOMic Tech Help 2 09-13-2001 11:54 PM
Removing W202 dash trim jjrodger Tech Help 2 06-23-2001 06:42 AM
5.25" dash speakers in '88 300E W124 Gebhard Car Audio and Multimedia 6 06-07-2001 02:19 PM
W202 Dash Lighting bmwscooter Tech Help 9 04-16-2001 07:57 AM



All times are GMT -4. The time now is 06:40 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2025, 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