Check fuses related to air conditioning. If they are ok and if you are familiar with both electrical work and have the required tools, read the factory service manual for diagnostic information. If the problem is electrical, ie: failed blower motor, failed control head or other electrical problem, the fix, while maybe not cheap, the repair could be a DIY activity.
If the problem is with refrigeration, repair may require special tools and the equipment necessary to evacuate then recharge the system.
Also, with a car that old from which the refrigerant has leaked you're looking at a replacing the drier, condenser and hoses. In that case, repair will not be cheap.
If you are not familiar with A/C work, take the car to an air conditioning specialist.