If you were close enough to me I could connect my OBD2 bus/traffic monitor tool: Vehicle Spy 3; and tell you if the car had a CAN bus. (If it does it will be for the Komfort Bus. For the DME the bus is ISO-9141-2 or KWP 2000. Even my 2008 Cayman S didn't use CAN for the DME.)
You can look at the OBD2 connector and see which pin locations are occupied.
Looking at the OBD2 connector the upper left hand pin location is #1 and the pin locations increase from left to right: 2, 3, 4, 5, 6, 7, and 8 is in the upper right hand corner.
The lower left hand corner is #9 followed by 10, 11, 12, .., and 16 in the lower right hand corner.
Pin # 6 is the CAN (J-2284) HIGH while pin # 14 is the CAN (J-2284) LOW.
Pin #7 is the ISO 9141-2 K-Line while pin #15 is the ISO 9141-2 'L-Line. These pins are used by KWP2000 and there is no way to know which protocol is in use other than attempting the proper discovery in the right order.
Pin # 2 is the J1850 Bus + line while pin # 10 is the J1850 Bus - line. (I do not expect these to be present.)
Pin #4 is chassis ground, pin #5 is signal ground, and pin #16 is battery power. Pins #1, 3, 8, 9, 11, and 12 are "Vendor Option".
'course, you realize even if the CAN pin locations are occupied this is not a guarantee the car has a true CAN bus and even if it does have a true CAN bus this is not a guarantee the A/C system will work in the car.