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 01-19-2005, 04:59 PM
Registered User
 
Join Date: Jan 2005
Location: Miami Florida
Posts: 48
Question NO AC and NO TACHOMETER?

I need all the help I can get with this one. I have been reading other Threads related to no AC and Tachometer, but have not been able to find one for a 1996 E320. Does anyone knows if both the AC and Tachometer are related? I also read that the Crank Speed Sensor may be the problem? Any sugestions? I welcome any advice.

Also my Cruise Control stoped working at the same time of the AC and Tachometer. All fuses are good.

I appreciate the help.

Reply With Quote
  #2  
Old 01-19-2005, 05:01 PM
Registered User
 
Join Date: Aug 2003
Location: New Orleans, LA
Posts: 305
my understanding is that if the relay that controls the AC is bad (labeled the "Klima" relay in some models, which is German for climate), it can cause the tachometer to stop working. Why? I have no idea, but I read that in some posts while doing searches on another issue.
__________________
2005 Mercedes C230k sport sedan, 6 speed
1987 Porsche 924S - 968-engined track car
Reply With Quote
  #3  
Old 01-19-2005, 05:08 PM
Registered User
 
Join Date: Jan 2005
Location: Miami Florida
Posts: 48
Thanks for the info. But I understand that the 1996 E320 does not have a relay and is only controled by Climate module or on and off swicth. Perhaps someone can confirm the info.

Thanks
Reply With Quote
  #4  
Old 01-19-2005, 05:15 PM
nellotare's Avatar
Registered User
 
Join Date: Jan 2001
Location: Wilmington, NC
Posts: 334
I have read that the tach "tells" the compressor that there are "revolutions" from the engine. If the tach fails, the compressor thinks the car has been turned off and therefore will not engage. A safety feature so you don't burn out compressor. I don't have this on my vehicle, but have read posts that indicate this scenario. Hope this helps a little.
__________________
Nello Tare

1982 300D (266,001 mi.) looking and running great

Previously owned:
1976 450 SLC
1983 300D
1976 300D
also
1982 Jaguar XJ6 (loved, but gone)
Reply With Quote
  #5  
Old 01-19-2005, 05:31 PM
pberku's Avatar
Registered User
 
Join Date: Oct 2003
Location: Montreal, Canada
Posts: 737
Quote:
Originally Posted by nellotare
I have read that the tach "tells" the compressor that there are "revolutions" from the engine. If the tach fails, the compressor thinks the car has been turned off and therefore will not engage. A safety feature so you don't burn out compressor. I don't have this on my vehicle, but have read posts that indicate this scenario. Hope this helps a little.
He is right, You have a system in your car that compares the speed of the engine to the speed of the AC compressor. If they are off by a certain percentage (I think 20%) the system than assumes that your compressor is jammed and immediately turns it off. The most likely cause of your problem is the engine speed sensor, or its related wiring. This sensor is also the one that feeds your tachometer its signal.

By the way, are you sure that you don't have a KILMA relay? Its typically located in-front of the firewall behind the Battery. Its usually the Relay that does the speed comparison and turns the AC compressor off if necessary.

You can perform a small experiment (will need two people). Turn the AC off and start the car. Look at the AC compressor while someone activates the AC system from inside the car. I bet that you will notice that it engages for a split second and than shuts off. It will repeat this action once you stop the engine and start it again. It will not come on again unless you turn the engine off.

If the above does happen, than my diagnosis is most likely correct.

Phil
__________________
'95 E300 Diesel, 264,000 Miles. [Sold it]
Reply With Quote
  #6  
Old 01-19-2005, 06:47 PM
Registered User
 
Join Date: Jan 2005
Location: Miami Florida
Posts: 48
Thanks a lot guys, I will defenetly will perform the two person procedure/test. On the 1996 E320 the battery is under the back seat and I have looked under every compartment, dash, engine and the only relays that I have found are inside the module compartment on the right rear of the engine compartment. I believe the relay module is called a K40 which has 6 relays inside. I also just finish checking the Crank Speed Sensor (I check it by disconecting it and the car would not start, once I reconected the cable the car started ).

I welcome any more Ideas.

Once again thanks in advance for your help,


Norman

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 10:02 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, 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