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 06-27-2013, 11:57 AM
pjc pjc is offline
Registered User
 
Join Date: May 2006
Location: Arlington VA
Posts: 278
W210 A/C not cooling (1996 E300)

Air conditioning not working this year--no cooling whatsoever. Worked okay last summer, and heat worked fine over the winter. I was hoping it was just low on refrigerant, but it won't accept any more through the low-side port. Compressor is original as far as I know.

CCU readings today (temps in deg C), with ambient temp 82F/27C, humidity 71%, CCU set to Auto/72F:
1 In-car temp – 33 (91F; this may be accurate, since I was driving the car in the sun for a few minutes)
2 Outside temp – 20 (obviously wrong)
3 Heater core L – 31
4 Heater core R – 31
5 Evapor temp – 30
6 Coolant temp – 83
7 Refrig press – 05
8 Refrig temp – 29

Error codes: CCU displays three error codes, which reappear after clearing and engine restart:
- B1459 (series interface (K2) connection to instrument cluster)
- B1422 (series interface (K1) connection to instrument cluster)
- B1226 (in-car temp sensor)

Other observations:
- Compressor clutch engages and disengages quietly (too quietly?) when EC button pressed
- No physical signs of compressor failure (leaks, burns, bad electrical connections, hissing)
- EC LED does not illuminate except when button pressed
- Rule out duovalve (no change in symptoms with hose clamped)
- Rule out serpentine belt, tensioner, fan clutch (all replaced last year)
- Rule out aux fan, blower motor controller (both recently replaced)

Sensors:
- CCU reading #2 is almost always 20C regardless of actual temp, but occasionally it flashes a value consistent with the LED temp display in the instrument cluster, which is accurate. This suggests the ambient temp sensor (in front bumper) works, but there's a signal problem between it and the CCU.
- CCU reading #6 is almost always 105C, but occasionally it flashes a reading that matches the coolant temp gauge in the instrument cluster.
- CCU #21 (engine speed sensor) always reads 25 (2500 rpm).
- CCU #22 (vehicle speed sensor) always reads 50 (km/h).
- In-car temp sensor appears okay physically (fan spins, wiring undamaged, receiving power), but perhaps it's generating a faulty signal

I'm inclined to rule out the evaporator temperature sensor since it generally gives a reading consistent with the cores.

Refrigerant pressure seems low and does not change by more than 1 bar (if at all) when EC button is pressed. I'm hoping that doesn't mean the compressor is shot. Maybe there's a blockage somewhere (expansion valve?)

What are my next diagnostic steps?

Thanks.

Paul
1996 E300D (W210), 185K mi

Reply With Quote
  #2  
Old 06-27-2013, 12:32 PM
uberwgn's Avatar
Registered User
 
Join Date: Jul 2005
Location: New England
Posts: 979
I don't know much about A/C, but I'd always start with an evacuation followed by the correct fill. These cars are a bit touchy in terms of having the correct charge, I know our 1998 certainly is.

__________________
1998 W210 diesel (wiped out by a texter)
Baum spring compressor "for rent"
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 11:00 AM.


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