1998 C280 w/ 132k mi. The AC is not cold. I noticed that the EC light is always on, and can't turned it off. Does the EC light needs to be off in order to activate the AC unit? I just got this car last week and not familiar this model. Any feedback is appreciated.

 

EC means economy...the light has to be off for a/c to work.

 

If you can't turn the EC light off and the air-co is not working, then most likely it is in safe mode to try to prevent damage to your compressor due to low refrigerant. Low refrigerant means you have a leak in your system somewhere and need to get that fixed first before recharging.

 

thanks for the advice.

 

If the EC light cannot be turned off, am i still able to charge the AC system w/ freon? If the AC system is not running, how am I going to put in the R134?

 

I just fixed this AC issue. I charged the AC system with one can of R134. But the EC light was still on and couldn't be turned off. Then I used the reset and delete features in the climate control panel (I did a search on this forum and found the reset and delete procedure) to clear the fault. Now the EC light is responding and the AC is cold. Thanks all for the help.