Got a 96 CL420 and the a/c packed up. The EC light is on all the time. I had it regassed as it was empty (so it obviously has a leak), but the EC light stays on and I still have no a/c.

I thought the EC light told you the a/c had quit, but regassing would turn the EC light off. Is there method to reset the light, or does it tell me I have another problem?

On the USA 1996 & later cars there is a sensor on the A/C drier bottle that can cause the lamp to stay on. Somewhat a common problem on these newer cars. 210-830-00-72 is the part number.

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Thanks MB Doc. There are 2 sensors, a larger one for the fans (I think), and a smaller one. Is it the smaller one you are talking about? If this is the one that measure pressure, then maybe its busted. I was going to measure the resistance across it, but I don't know what it should be anyway, so didn't bother. And of course you can't jumper these sensors any more.

Am I right in thinking that the EC light should go out if it sees pressure at that switch?

MB Doc, I had a look at the wiring diagram, and the sensor you are talking about is a refrigerant temp sensor, and is wired in series with the internal air quality sensor. Can you explain how this stops the a/c coming on and lighting the EC light? Cheers.