HVAC maintenance is a scheduled inspection and cleaning of your furnace, air conditioner, heat pump or mini-split, done before the season it is needed for. In Sunnyvale, Santa Clara and Cupertino that means cooling checks in spring, before hot spells from June to September, and heating checks in fall, before the systems run from November to March. A maintenance plan simply puts those visits on a calendar so they happen.
What an annual tune-up checks
Cooling (air conditioner or heat pump in cooling mode)
- Filter, blower and the indoor coil, where most airflow problems start.
- Outdoor coil cleaned of dust, leaves and debris so the system can shed heat.
- Condensate drain cleared and the float switch tested, so water does not end up on a ceiling.
- Run capacitor measured against its rating, and contactor contacts inspected for pitting.
- Amp draw on the compressor and fan motors, and electrical connections tightened.
- Temperature drop across the indoor coil, a first sign of low airflow or a refrigerant leak.
- Thermostat operation in cooling.
Heating (gas furnace)
- Igniter and flame sensor, the two parts behind most no-heat calls.
- Burners and flame appearance, and a visual check of the heat exchanger where it can be seen.
- Inducer motor, pressure switch and high-limit switch.
- Flue and venting connections, and the gas connections at the furnace.
- Blower operation and temperature rise across the furnace.
Heat pumps also get a check of the reversing valve and defrost operation, since they heat and cool with the same outdoor unit.
Seasonal maintenance: spring and fall
| Season | Visit | Why then |
|---|---|---|
| April to May | AC or heat pump cooling check | Weak capacitors and dirty coils fail on the first hot afternoon |
| September to October | Furnace or heat pump heating check | Igniters and flame sensors fail on the first cold night |
| After smoke days | Filter check | Wildfire smoke loads filters fast in late summer and fall |
A tune-up booked before the season also lands on a calmer schedule than a repair call booked during a heat spell.
Filter replacement service
A clogged filter is behind frozen AC coils, furnaces that shut down on the high-limit switch, and weak airflow in general. Standard 1-inch filters usually need replacing every one to three months; thicker media filters last longer. Higher-efficiency filters catch more fine particles but also restrict more air, so the right rating depends on what the blower and ducts can handle. If you would rather not track it yourself, a filter replacement service handles it on a schedule. For smoke and allergy concerns, see indoor air quality.
Maintenance agreements
A maintenance agreement books the spring and fall visits for you, so they happen before the season instead of after the first failure. The terms are written down before you sign: how many visits a year, which equipment is covered and what each visit includes. Nothing is replaced during a tune-up without your approval. If a technician finds a worn part, you get the findings, the repair options and the cost factors first. City pages: maintenance agreements in Santa Clara, annual tune-up in Sunnyvale and seasonal maintenance in Cupertino.
Ductless and mini-split maintenance
Ductless mini-splits need more frequent filter attention than central systems: the washable filters in each indoor head should be rinsed every few weeks during heavy use. A yearly service cleans the indoor coil and the blower wheel, checks the drain and inspects the outdoor unit. See ductless maintenance.
Commercial and multifamily maintenance
Offices, shops, restaurants and apartment buildings run their equipment longer hours, so rooftop units need filters, belts, coils, drain pans and economizers checked more often than a home system. Restaurants load coils with grease faster. A preventive program sets the schedule around business hours. See commercial HVAC and commercial maintenance.
What maintenance can and cannot do
Maintenance keeps a sound system working the way it was designed to. It will not fix undersized ducts, a system sized wrong for the house, or a compressor near the end of its life. What it does give you is information: a record of readings from year to year that shows whether a repair makes sense or whether it is time to plan a replacement calmly, rather than in a heat spell. Repair before replace starts with knowing what you have.