Short answer
A tune-up is a check of the parts that fail most: capacitors and contactors, the condensate drain, coils, refrigerant readings, the blower, and the filter, plus the heating side before winter. For a heat pump, which works in both seasons, the usual schedule is twice a year: spring for cooling, fall for heating.
Upstate systems don't get an off-season. At GSP, July highs average 90.3°F and January lows average 32.1°F (National Weather Service, 1991–2020 normals), and many homes here heat and cool with the same heat pump. Twice a year beats once in August.
What a cooling tune-up should cover (spring)
- Thermostat operation and settings.
- Filter condition, and the right size and type for your return.
- Capacitor readings against their rating, before a weak one leaves you without cooling.
- Contactor condition: pitting, burning, sticking.
- Electrical connections tightened and checked for heat damage.
- Outdoor coil cleaned and fins checked, and the area around the unit cleared.
- Refrigerant pressures and temperatures, and signs of a leak.
- Indoor coil and blower checked for dirt and airflow.
- Condensate drain line cleared, pan and float switch checked.
- Temperature drop across the coil and overall system operation.
What a heating tune-up should cover (fall)
- Heat pump heating mode, defrost operation, and the reversing valve.
- Auxiliary heat strips, their sequencers or relays, and how the thermostat stages them.
- On gas furnaces: igniter, flame sensor, burners, inducer, pressure switch, venting and condensate drain.
- Limit and safety switches.
- Blower, filter and airflow.
- Electrical connections and controls.
Whatever is wearing out gets flagged with an explanation, so you can plan for it instead of finding out on the hottest night in July.
What it costs
Ask what the service call costs when you call. For what drives the price of a repair or a new system, see what HVAC work costs.
Why it matters more here
Drain lines
Your AC pulls a lot of water out of humid Upstate air. When the drain line clogs, that water backs up. In an attic, that means a ceiling stain. In a crawlspace, it can go unnoticed for a long time. Clearing the drain is one of the most useful things a tune-up does. See water around the air handler.
Capacitors
Heat wears capacitors down, and a weak one often keeps working until the hottest day of the year. Testing it in spring catches it early.
Filters and coils
A clogged filter or dirty coil strangles airflow, which can freeze the coil in summer and overheat the system in winter. EPA guidance on home air filters suggests using a filter rated at least MERV 13, or as high as your system will accommodate, and notes that no filter removes every pollutant.
Signs you shouldn't wait for a tune-up
- The outdoor unit hums but the fan doesn't spin.
- Water in the drain pan, around the air handler, or on a ceiling.
- Ice on the copper line or the indoor coil.
- Aux heat running constantly, or a power bill that jumped.
- New noises or smells. See strange noise or smell.
Common questions
How often should an HVAC system be serviced in South Carolina?
Twice a year is the common recommendation for heat pumps, which run in both seasons: a cooling check in spring and a heating check in fall. A system with a gas furnace and a separate AC benefits from the same schedule.
How often should I change my air filter?
Check it monthly and change it when it looks dirty. Thicker media filters last longer than one-inch filters. A clogged filter is one of the most common causes of frozen coils and weak airflow. EPA guidance suggests a filter rated at least MERV 13, or as high as your system will accommodate.
What can I do myself between visits?
Change or check the filter, keep plants and debris clear of the outdoor unit, rinse leaves and grass clippings off the outside of the outdoor coil with a garden hose (power off first), and keep an eye on the condensate drain and pan for standing water.