air con

chrisriggs

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Joined
Aug 16, 2008
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3
Location
Plymouth Devon
Car
1999 C250
Hi Folks, I am a new member can anybody help please. First Mercedes 1999 C250 TD, very pleased with it. Problem with air conditioning. Been back under guarantee for few minor problems but air conditioning not working, system has been charged, dye and pressure tested and not showing any leaks, got fed up with keep going back and getting nowhere. No visible flow in sight glass so suspect compressor or clutch but Haynes Manual useless. Any way of checking clutch please.
Thanks for any information.
 

Dieselman

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Jul 13, 2003
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Peugeot 403 Convertible
If the system is definitely charged you should meter the voltage into the compressor clutch, it should have 12v when energised.
A simple test is to bang 12v straight into the clutch and see if the system works., if so it has to be either the controller or the relay at fault.

Welcome to the forum.



p.s.
Can a Mod please move this to the Engine section.
 
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chrisriggs

New Member
Joined
Aug 16, 2008
Messages
3
Location
Plymouth Devon
Car
1999 C250
If the system is definitely charged you should meter the voltage into the compressor clutch, it should have 12v when energised.
A simple test is to bang 12v straight into the clutch and see if the system works., if so it has to be either the controller or the relay at fault.

Welcome to the forum.



p.s.
Can a Mod please move this to the Engine section.
Thanks Dieselman, couldnt find any terminal on compressor so had to cut wire, no voltage showing, putting 12v to clutch side of wire can hear a solenoid slamming in but no visible fluid movement. Switched off ignition and engine runs on until voltage removed. Relay B under main fuse box seems to have overheated at some time any way of checking it.
 

cowley

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Sep 15, 2014
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2
Location
Lahti Finland
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c250 TD
C250 TD air con

I have a 1999 C250 TD, I seems I have to have the air con topped up every spring, it works fine for the summer then, but is this normal? I have to pay about 80€ every year for this. :mad: BTW I had the air con checked for leaks and was told that there is no leaks.
 
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m2mb

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Earth (blue pale dot)
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E220 CDI 2008, E220d 2019
I once accidentantly detected a leak (after dealer failed with machine, coloured gas etc) by going into my closed home garage at 11pm to get something from the car. A clearly visible sound could be heard, of air leaking somewhere which was proved to be an a/c pipe; that was later fixex. it would not leak during the day or it could not be heard - you need absolute silence to do this and you also need the a/c to be fully charged on that day and you also need to have turned on the system and car for some time so that driving temperatures are achieved. If the leak is minor you might hear it in the still of the same night!!! if its huge then all gas would have leaked already during the day so...

by the way can you not feel the clutch engaging? an dead compressor is almost always noticeable, i think.
 

Howard

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Apr 23, 2004
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18,624
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Toad Hall
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CLS 500 / A 150
There will undoubtedly be a leak , albeit a small one hence why it takes a year to leak out.

Pinprick hole in the condenser is my bet.
 

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