W124 Air conditioning

1986-1995 : 200TD, 200CE, E200, 260E, 300E 2.6, 300E 2.8, 300E, E320, 400E, E420, 500E, E500, 300CE, E320, 230TE, 300TE, 300D 2.5 TURBO, E300 DIESEL, 300TD, 300E 4MATIC, 300TE 4MATIC, E36 AMG
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Dernburg Wagon
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Joined: Mon 04 Feb, 2008 11:49 am
Model you own: w123

W124 Air conditioning

Post by farmbenz » Thu 14 Jan, 2010 12:01 am

Hi all,
I have an ongoing problem withthe air cond on our 124. When you test the a/c it works well, shows minimal bubbles through the sight glass (ie is correctly filled), but after driving a while it fails to cool. Problem is intermittant but will pretty reliably fail on a hot day! Cycling off then on again makes no difference. When it plays up I can test it later in the workshop and it functions fine. 12deg center vent temp etc.
Problem seems related to under bonnet temperature.
When tested aux fan works correctly in stage 1 and stage 2.
Does anyone have any clever ideas out there?

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450 SEL 6.9
Posts: 471
Joined: Thu 19 Oct, 2006 11:40 pm
Model you own: w126
Location: Adelaide.

Re: W124 Air conditioning

Post by tugpilot1 » Thu 14 Jan, 2010 8:16 am

If it's a York compressor, it could be as simple as this!

I wonder how many owners have been charged for unnecessary work on their vehicle's air conditioner.
Experiencing an on again/off again situation with the cooling air coming into the car, I took it to my tame expert who, after checking that sufficient voltage was getting to the main body of the York compressor, quickly informed me that the trouble was more than likely to be found in the driven clutch.

He proceeded to remove the item in question only one bolt had to be undone and, sure enough, he was correct. After cleaning off the collected grime and re-installing the part, the air conditioner ran as it should.

It seems that, over time, grime buildup results in a drop in the voltage available to operate the clutch. Eventually, it fails to operate.
Naturally, this will always happen on the hottest day of the year.
The point is, the job took about 20 minutes and no parts were required.
Worth remembering.
See photo at http://i145.photobucket.com/albums/r240 ... Clutch.jpg

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Location: Adelaide.

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OZBENZ moderator
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Joined: Wed 07 Jun, 2006 10:44 pm
Model you own: w107
Location: Darlinghurst, Sydney.

Re: W124 Air conditioning

Post by Fotografa » Thu 14 Jan, 2010 8:20 am

tugpilot1 wrote:If it's a York compressor, it could be as simple as this!

Weren't all W124's fitted with Denso Compressors?

Maybe, if it works at the start, and then fails it could actually be icing up? (I'm not an AC expert, so I could be completely off the mark, but just a thought)
1981 500SLC 040 Black on Black leather
Children that have left home:
1973 R107 450SL Icon Gold
1974 C107 450SLC Black
1971 W114 230 Arctic White
1974 W114 280E Signal red
1981 W123 280E Signal red
1974 W114 280CE Silver
1975 W114 280CE Metallic Red

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Mercedes Demigod
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Joined: Thu 28 Jul, 2005 11:33 am
Model you own: w124
Location: Hawthorndene SA

Re: W124 Air conditioning

Post by Hendrik » Thu 14 Jan, 2010 12:18 pm

So what you are saying is that the system works until there is heat under the bonnet?

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Joined: Fri 24 Jul, 2009 10:52 pm
Model you own: w124
Location: Box Hill Vic

Re: W124 Air conditioning

Post by suitcaseau » Sun 28 Mar, 2010 5:38 pm

Have had problems with mine for ages. This summer first of all needdd regassed them worked perfectly for about a week. The packed in. Took it to the local MB specialist, had a new control unit fitted at over $360 for the used unti. Again worked for a week or so them packed in. Took it back, this time it seems the relay. Couldn't get anew one at short notice so the mechanic fixed the old one. This time it worked for about a week then started to work intermittently; ie it would work on the way to the takeaway shop but not on the way back, then packed in altogether. So I was mucking about with it yesterday and in the course of removing the relay it came on. I kept taking it in and out and sometimes it kicked in and sometimes not. So I used the motorist's friend WD 40 and cleaned the terminals then sprayed down the socket. Guess what? Working a treat.

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Posts: 93
Joined: Fri 24 Jul, 2009 10:52 pm
Model you own: w124
Location: Box Hill Vic

Re: W124 Air conditioning

Post by suitcaseau » Sat 28 Jan, 2012 2:27 pm

Air con problems again. I had the gas topped up just before christmas as it wasn't working (and no gas visible in the optic). It took quite a bit of gas. Worked a treat. Then last week it stopped working when it was really hot (and no gas visible in the optic) but started working again later in the day when it had colled a little. I had exactly the same problem believe ot or not on the same day last year (Australia Day), when it failed to work when it was really hot but resumed working later that day when it had cooled a bit. Getting a bit frustrated, frankly. The aircon has been the only real problem i have had with the car since i bought it. have replaced the relay and the controller and had it regassed (an annual event). has any one got any answers? It is a 95 E280.

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Mercedes Demigod
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Model you own: w204
Location: Melbourne

Re: W124 Air conditioning

Post by Ivanerrol » Sat 28 Jan, 2012 2:35 pm

Shouldn't require re-gassing every year - you must have a leak.

Alternatively the '90's cars were plagued with weak evaporators (combination of using aluminum and ferrous metals and the solder used). Better hope this is not the problem as the evaporators are cheap however the job to replace them is rather large.
W211 - E240
W204 - C280
W210 - E240
W202 - C200, C180, C180
W126 - 380SE , 380SE (Ex SA Import), 560SEL
W124 - 300e, 260e (ex Japan)
W111 220s (Indonesia) 4 speed manual column shift
W123 230
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W140 420SEL
W210 E240
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W201 190e 2.6 (ex U.K.)

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Model you own: w124
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Re: W124 Air conditioning

Post by DBW124 » Tue 31 Jan, 2012 8:39 am

Last week I was wondering if mine needed re-gassing as it did not seem that cold (though on Sunday did have condensation forming on the centre vents).
W124 E 280

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