Some of the more typical things you should expect during an AC tune up are:
A thorough cleaning of the condenser coils. This improves efficiency (which has a direct influence on energy costs) and can minimize wear and tear on your system.
Evaluation of the coolant level to aid in the maintenance of peak operational performance.
Lubrication of all moving parts to reduce friction and wear, which can raise your energy bills.
The thermostat will be fully calibrated to ensure optimal performance.
An examination of the ductwork for potential energy loss.
Tightening and inspecting all electrical connections to ensure that the system is operating safely.
Examine the blower motor's performance and the condition of the blower belt.