Well, things have changed for the better!! I decided to post my last message anyway and update things with this one.

I obtained a copy of MB Technical Bulletin that addressed the "Economy" light being on all the time. I followed their recommended procedure and my light is now off!!

Here it is:

37/99-2 GROUP 83 - MODEL 210, CLIMATE CONTROL "EC" LAMP ON: *** UPDATE TO MB-NET MESSAGE NO. 220 DATED APRIL 16, 1999, DTB 17/99 ***: If you receive client complaints on model 210 of "the EC lamp on", please check the system according to the published diagnostic and service procedures. Check if the version coding is correct. Replace the refrigerant temperature sensor in every case. If the refrigerant quantity, temperature or pressure sensors are within the specified values, the low refrigerant level indication should be switched off via the HHT or via the on-board diagnostics (P2 value) as described below. Do not replace AAC push-button modules for this complaint.
Please note that "EC" lamp low refrigerant indication is a redundant feature. Disabling this feature does not compromise the safety of the AC system, because the AC compressor will switch off if low refrigerant (level) pressure is detected.
Switching of the "EC" lamp low refrigerant level detection via the AAC Push-button Control Module can be accomplished as follows:
Switch ignition to position 2.
Set the left temperature to "HI" and the right to "LO"
Switch the ignition off.
While holding the "REST" button, switch the ignition to pos. 2. On the left side of the display, "P1" will be blinking and on the right side, the version code is
displayed. Press the "EC" button, no change is needed for the P1 value.
Press the "EC" button again. "P2", will be blinking on the left side of the display and the value on the right side.
Record this value. Using the right side temperature (red) button add 16 to the displayed value.
Press the "EC" button to store the updated version code.
Turn the ignition off and on again. Reset the left and right side temperatures to 72?F (by pressing the red and blue buttons at the same time).
For warranty, please use Damage Code 83752 04.

57/99-2 GROUP 83 - MODEL 210, CLIMATE CONTROL "EC" LAMP ON: *** REPLACES MB-NET MESSAGE NO. 461 DATED AUGUST 25, 1999, DTB 37/99 ***: On Model 210, for conditions of the EC LED lamp on although the button has not been pressed, please replace the refrigerant temperature sensor to resolve this condition. The refrigerant temperature sensor may absorb moisture may cause incorrect values to transmit to the control module causing the air conditioning system to switch off. For warranty, please use Damage Code 83752.

There is also an earlier version of this bulletin that is exactly the same except that it leaves out the recommendation to change the refrigerant temperature sensor.

Want to thank everyone for your assistance.

Len