The AC may stop working due to a refrigerant leak from the condenser. GM has developed and updated condenser and mounting bracket to help prevent the replacement condenser from failing in the same manner.
Car Problem Reports
Pontiac Montana AC Condenser May Develop Refrigerant Leaks
Pontiac Montana Problem
Average Mileage: 122,000 mi (75,000 mi - 150,000 mi)
Visitor, 2001 Pontiac Montana, 128,000 mi
Leaking condenser coil on top edge by Radiator cap........ taking to the shop
visible refrigerant leak at condenser. Replaced condenser.
Visitor, 2002 Pontiac Montana, 150,000 mi
my "mantana" has the same problem with the leasking condensor coil-dye in the refrigereant helped me find it after several wasted trips to the dealer.
ac failed after 5 years, lines rotted out, we live in MA with salt on road in winter, did not replace due to cost