Air conditioning tends to be invisible until it stops. Long before that, a neglected system quietly costs money — a blocked filter or fouled coil forces the equipment to run longer to reach the same temperature, and every extra minute is on your power bill.
How systems lose efficiency
Dirty filters: Restrict airflow, forcing longer run times. The cheapest and most neglected maintenance item there is.
Fouled coils: Dust on the heat exchange surface acts as insulation, directly reducing the system's ability to move heat.
Blocked drainage: Condensate trays and drains block with sludge, causing overflow, water damage and microbial growth.
Refrigerant issues: A system low on refrigerant has a leak. Topping it up without finding the leak treats the symptom.
Worn components: Fan bearings, belts and contactors wear predictably and are far cheaper to replace before failure.
Air quality and hygiene
Ventilation systems move air through the space people occupy, so anything growing inside them is distributed with it. Damp, dust and organic debris in ductwork, drain trays and on coils can support microbial growth, and are a known contributor to poor indoor air quality complaints.
This is also why ventilation matters after any chemical treatment in a building. Running the system on fresh air rather than recirculation draws outside air in and clears residual vapour far more effectively than simply waiting.
What a service should include
Clean or replace filters, and note the correct type and size for future changes.
Clean coils and check the condensate tray and drain line for blockage.
Check refrigerant pressures and inspect for leaks.
Inspect electrical connections, controls and safety devices.
Check fans, belts and bearings for wear and noise.
Verify thermostat calibration and confirm actual output temperatures.
Signs a system needs attention
Running noticeably longer to reach the set temperature, or never quite reaching it.
Uneven temperatures between rooms or zones.
New noises — rattling, grinding or squealing.
Musty odour when the system starts.
Water marks near an indoor unit, or ice on refrigerant lines.
An unexplained rise in energy cost against similar weather.