AC inside control panel on 2000 Mercedes-Benz E430 4MATIC

I can't switch my AC from EC to recirculating mode on the control panel. The compressor guage low side reads 70 psi and will not engage. Is it possible that my EC sensor under the dash is bad? Please help.

Asked by for the 2000 Mercedes-Benz E430 4MATIC
you need to scan the climate control system and find out what codes you have. EC means "economy" and the compressor will never come on while it's in this mode. there is no EC sensor.