blower fan in mercedes c200 some times comes on .but not all the time on eco. do not use a/c. wiring ok to fan?

ON a MERCEDES when you hit the ECO button, it DELIBERATYELY shuts down the A/C compressor AND the cooling fan. You have a cooling safety switch near your cylinder head that willc ause the ELECTRIC fan to engage should the engine begin to over heat.ALL air conditioning system engage the COOLING FAN when the A/C Compressor goes on. THis is to prevent the refrigerant from boiling. WHen the ECO button is depressed, it shuts OFF the compressor in order to help save a small bit of GASOLINE. Later model A/C compressors are much more efficient than older units and do take as much power drain, but they will cost you a mile or two in MPG.<<<<<<<<I reread your problem. I f youa re writing about the BLOWER motor itself going of, then you have WORN CONTACT BRUSHES within the BLOWER mtor. Or a bad SIGNAL from your HEATING RELAY. After many years of use it is common for ALL blower motors to lose theirr carbon contact brushes from wear. I have learned to take this motor out, and ggo to a starter alternator store, wheere they can install NEW brushes. On MERCEDES blower motors, there is a replacement set of contact brushes aviailable, but HARD to find. CALL your MB dealership for NEW brush prices. THis is cheap than buying a new or replacmentblower motor. GOOD LUCK!!

Eco just means that it is not using the Air Con part of the system. You clearly have climate control in your car and the system controls the fan speed as required to try to move air to maintain the temperature that you have set it at.

Assuming that the cars cabin temperature sensor is working correctly, there is usually a sunlight sensor too, then all woulsd seem to be normal.

I think thats what Eco does? To save fuel, hence economic.