Safe DIY maintenance:
Change air filters monthly
Clear debris around outdoor AC unit
Keep return air vents unblocked
Dust supply vents with vacuum attachment
Replace thermostat batteries
Clean return air grill with vacuum
Requires professional:
Refrigerant handling (illegal without license)
Electrical component work
Duct sealing or modification
Coil cleaning (requires chemicals and expertise)
Blower motor maintenance
Any system diagnostics
Why professional service matters:
HVAC systems contain 220V circuits (dangerous)
Refrigerant handling requires EPA certification
Improper maintenance voids warranties
Misdiagnosis leads to expensive unnecessary repairs
Specialized tools required for proper service
Focus your effort on filter changes and keeping systems clear of debris. Leave technical work to licensed professionals. Your time is better spent on tasks where professional expertise isn't needed.