air conditioning

Hi
Mercedes E300 diesel 1996. I had the aircon gas charged and it appeared to be not working, I took it back to the garage and they found it to be working
OK. Sure enough, on that occasion, I can confirm it worked. It is now not working again. Before I send it to the dealers, I would like to know what you guys think may be the likely cause, I have bad experience in the past. I was told it may just be a 'lazy switch', but I suspect the dealer will want to change the pump and everything else attached to it. I know the two dials on the dashboard appear to be working, it throws out heat very well, the EC switch appears to be working OK also as I can hear the change of pitch of the fans.
I would really appreciate some help so that I know what the dealer is talking about when I send the car in.
Much appreciated.
Charlie Brown London
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When it is not working... is your EC light on constantly and you can't turn it off? If so, it is most likely to be your evaporator sensor that went bad...very typical on W210.
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On Sun, 6 Jun 2004 15:45:42 +0100, "Charlie Brown" wrote:
With the engine running lean over the engine and get someone to switch the a/c on then after a few seconds off again. You should be able to hear an audible clicking sound under the bonnet - this is the electronic clutch engaging the a/c compressor. If this isn't happening it could be for lots of reasons. Low internal pressure, a faulty relay, a faulty switch, an open circuit, the system icing, a blown fuse or something else!
There is also a sight lens on the top of the evaporator. Give it a rub with a cloth so it's clean. Now with the a/c runing you should be able to see the refrigerant (technically not Feron as that is the of the old R12 refrigerant that isn't used any longer) flowing through the evaporator. If you can't see anything moving you may have a leak or you may have moisture (water) in the system. Water will turn to ice in the system and cause a blockage... once it has melted then the a/c can work properly again. This can cause the system to look as if it is only working intermitently. This is likely if the system has been apart recently, and left in the open air for a while. The moisture in the air can get trapped in the system and cause icing.
300 Essie
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1994 Mercedes E280 [W124] 99,000 miles (R.I.P)
1992 Mercedes 300 SE [W126] 230,000 miles
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