Outdoor unit (condenser)
- Shut off power and inspect the electrical disconnect
- Test the run capacitor against its rating
- Inspect the contactor for pitting or burn marks
- Check the fan motor and blade, and tighten mounting
- Clean or rinse the condenser coil, inside-out where possible
- Check the unit is level and clear of vegetation
Refrigerant system
- Measure operating pressures, superheat and subcooling
- Look for oil spots or frost that can indicate a leak
- Inspect line set insulation (it often deteriorates in attic heat)
Indoor unit (air handler or furnace)
- Inspect the blower wheel and motor, and test the capacitor
- Inspect the evaporator coil where accessible
- Flush the condensate drain line, then test the float switch
- Inspect the drain pan for rust or cracks
- Check or replace the filter
Controls and performance
- Verify thermostat operation and calibration
- Measure the temperature split between return and supply air
- Check amperage draws on motors and the compressor
Heating season add-ons
- Gas furnace: inspect burners, igniter and flame sensor, check the heat exchanger, test safety switches, and check for CO
- Heat pump: test defrost operation, the reversing valve and backup heat strips
After the visit
A good technician will tell you what they found, what's wearing out, and what can wait. That's useful information even if nothing needs fixing today. Learn more about AC maintenance or request a tune-up using the form.