1997 Pontiac Montana Coolant Leak

The van is not overheating. The coolant seems to be leaking under the reservoir area which is located on the front part of the driver's side. It is most noticeable when I am letting the van run just parked in my driveway. Basically all the coolant in the reservoir seems to have leaked onto the ground. What do you think? I don't want to get taken at the mechanic shop. Also, another problem is the A/C is noticeably cooler on the passenger's side than the driver's side. Very unusual. Thanks for your help!