Maintenance of Air Conditioning Systems includes

Checking operation of the different zones and motor
Checking compressor running current and condenser fan operation
Inspect Condenser coil and indoor coil

Inspect electrical components are in good physical condition and check for hot joints
Check controller functions are all operational
Reset clock if required
Check the air flow is unrestricted
Inspect and clean air grilles
Inspect and clean return air grilles and filters
Check the gas levels and running pressures are within specification
Check and clear condensate drains as required
Check flexible ducting for any leaks and issues