Mercedes: AC and headlight issues, late model cars, battery cables

Question
Hi,
I have E240 2005 model, recently; some issues start to appear such as the AC. AC on the left hand side is not as cold as the right hand side (both front and rear). The other issue is also recently I have replaced the computer battery and also the main battery and since that time the headlights are lower than normal and most of the time I use the high beam to see. Appreciate your help.

Answer
Usually weak lights are the result of low battery or bad connections. These late model cars use such small wires that they will heat readily when there is a bad connection. The heat means less juice to the lights. I would remove the battery cables (-) first then (+). Clean the terminals and make sure that all the associated wires are in good conditions. Pay particular attention to all the wires entering the terminal. After cleaning reinstall the terminals (+) then (-) and tighten very well.
You did not relate why you replaced the battery. If it is because it was not taking a charge then you may have an alternator or voltage regulator problem. Remember that the battery just hold juice in reserve for cranking. All accessories get their current from the alternator when the engine is running.
Your differential in temperature of AC between left and right may be a result of servos not receiving the proper voltage to properly mix the air on the passenger side. Or if the diverted flaps are vacuum actuated it could be the result of a leak.
Let me know what you discover.
Good Luck
Rob