I had one where the door seal was letting in water.
Leave the passenger side window cracked open or the windows will fog up.
We are trading some of our kenworths because they brake down so much
I've driven multiple Kenworths, a few of which were my assigned tractor and never had this issue. Some of our newer Macks have had issues of water leakage though which would drip right into the CB radio area.
some do leak through the right clearance light. I drive a 273series KW ( I want my Mack back ) had bad leak issue shop sent it out to body shop, was told " The KW has an extension on back of cab, the seal between that and the cab was the problem " body shop replaced seal. It solved the problem FOR AWHILE. It leaks again in heavy rainstorms. It starts right side when you turn left to any degree it flows in the ribs of the floor mat makes it loo like it's coming from everywhere