Hi, this is Martin in Ohio. Our car is a 1998 MB 320CLK with 60,000 miles. Recently, the climate controls have begun acting strangely. Can't get the Auto switches or the EC switch to turn off. Not responsive to finger touch. Also, the air con is not working - is this because the EC switch will not turn off?? Owners handbook says aircon compressor will not engage if EC switch is on? The only switches that seems to operate properly are the Recirculate switch - when this is switched off, then EC will go off - and the Fan switch which can be turned down to zero and the whole system goes off.

Very frustrating. Have had the car since new and no such problems. However, long out of warranty and would like to be able to at least describe the issues to a local shop and try to find some trouble shooting path.
Not much help in the owners handbook.

Thanks for any help or advice
Sincerely,
Martin

When this light stays on this usually indicates a fault within the air conditioning/heating system. A fault has been detected and a code has set. The way this has to be corrected is a scan tool has to clear and or diagnose and correct the fault before it will become fully operational again. Normally most aftermarket scan tools won’t be able to communicate with the Air conditioning system and a dealer might be the only option for this. This is a common problem when a fault occurs. If the fault that was detected was a low on Freon or Freon pressure fault there is an updated coding that can be done to this vehicle so that way your car doesn’t check this and set off a fault for it but a dealer would have to set this coding on your vehicle if it hasn’t been done already;

And,

Your Climate control unit may have to be reset. The reset works as follows: With the key in the ignition and in posistion 2 push both the defrost button and the recirc button (at the same time) for five seconds or untill the led lights in those buttons begin to flash. Wait for 30 seconds or untill the led's stop flashing. Switch off the ignition. Check the evaporator temp sensor and pressure sensor for correct functionality