Yes, a clogged condensation drain will indeed cause the problem you describe. Let the car cool off, raise it safely and get underneath. Look above the front of the transmission and you will find the condensation drain in this area. Carefully clean it out with a coathanger or something. If doing so brings forth a gush of water, you will know that this is your problem.

It does not necessarily leak water on the floor if the drain is plugged up.

Hope this helps.

__________________
2001 SLK 320 six speed manual
2014 Porsche Cayenne six speed manual

Annoy a Liberal, Read the Constitution