1997 S320 A/c Ec
 

I have a 1997 S320- the EC light remains on and, as a result the AC compressor does not go on. Is this because of low refrigerant level OR a bad relay? If it is a bad relay, which relay operates the compressor? Klima?

What is the EC light and how do you know that this light is related to a/c control ? There are a lot of components that combine to control the compressor, and if you have the Klima relay like I have on my 87, 260E, then there is a step by step process I have posted to test the compressor circuit.

http://www.peachparts.com/shopforum/diesel-discussion/158591-ac-still-not-working-after-ac-conversion-87-300sdl-5.html

See this one too - http://www.peachparts.com/shopforum/tech-help/86110-210-chassis-climate-control-problem.html?highlight=economy+light

The EC switch turns off the compressor to revert the system to regular ventilation (no a/C). If the light stays on, your refrigerant charge is low, it is a failsafe mode.

Now, I just hope yourrefrigerant level is not low because of a leaking evaporator...