I worked for Zexel and Behr Climate Systems for 11 years, both automotive and truck HVAC suppliers. The "cloud" you saw exiting the center vents is not steam, but condensed water vapor. In cooler ambient temperatures, the evaporator core can develop a "supercooled" state when the refrigerant charge is low. The refrigerant is expanding more than normal because the low pressure side of the system is too low, creating a colder than normal evaporator core temperature. I've actually seen ice crystals blow out of car vents under these conditions and the evaporator core freeze over completely.


Check your refrigerant levels and I suspect you'll find it low.

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2016 F15 x35i
2014 F32 428i


2004 E46 325i sold at 123,600 miles
2002 E53 3.0 sold at 388,801 miles
2001 E46 325i sold at 66,000 miles


1970 Firebird Under restoration