Hey Gang - i have a problem with my '79 300SD air conditioning. I have had the car for 2 years and all of the sudden, there is condensate from my AC unit building up in the rear passenger seat under the carpet. I know it's not coming from outside, cuz it happened after a week of no rain. i have looked at all the obvious drain tubes in the engine compartment and they are working fine. Any experiences or recommendations that might help me identify root cause?

Thanks - JB