Mercedes: Mercedes ml350 2005 rear ac fan doesnt turn off, climate control system, resistor circuit

Question
Mercedes ml350 2005 rear ac fan doesnt turn off even if the power is off. It drains the battery so the battery is disconnected now. Thsi car is not in the USA and when a diagnostic is run, errors give saying:
Error
-73D
-72D

Any clue?

Answer
Bob,
There may be a problem with the rear air control switch. If it has a speed scroll control that may have a bad resistor circuit. The rear fan may be part of the total climate control system. A schematic would be necessary to trouble shoot the circuits.
Look to see if there is a front or rear override switch and make sure it is in the off position.
the -73D and -72D codes are new to me. You may be able to locate an independent mercedes shop that will give you the fault for these codes.
Good Luck
Rob