iin my 2007 TL, I have to lower the temperature setting to 67 to get what I used to get at 70.

 

I would suggest that you attach some gauges and check the refrigerant level. If you want to be cheap, stop by Walmart and pick up a can of refrigerant that has a gauge and you can add it yourself for under $50.

 

Might be a good idea to insert a small A/C "stem type" thermometer into the top center vent, to determine the exact cold air output at both 70 and 67 degree settings. Center vent, cold air output on my 2003 TLS, with 230K, never opened or serviced A/C system, shows between 34 and 38 degrees, dependent on ambient temperature and driving conditions, regardless of the temperature setting. Sometimes, even though i normally leave my temp setting at 68 degrees, the vent output temperature feels warmer than it could be. A glance at the thermometer though, confirms the output air temp is right where it should be, in which case i lower the the setting to 64 degrees, which increases the blower speed and creates the illusion that the output air is colder. Normally, the only time i adjust the temperature setting, is when I'm driving for an extended period, and the cabin becomes too cold. At that point, I adjust the setting to 70 or 72 degrees, and the cabin temperature becomes comfortable again. The temperature gauge will tell you if your A/C system is operating as designed.