flashing rear a/c

[benny10]

I have seen this problem listed on here but the problem was not solved??, I have ML270cdi, the rear a/c flashes red when i try activate the rear windows(they dont work with rear switch or front switch) putting the child lock on the flashing stops but rear windows still do not work .on locking the car the rear A/c flashes red constant and yes flatens the battery so i have had to unplug the rear housing to stop the flashing and the batery goning flat,but still the rear windows do not work with the front switch.