A season-by-season HVAC maintenance calendar
Most HVAC failures are maintenance failures, and most of that maintenance takes under an hour a season. The rest is booking a technician before the week everyone else calls.
Spring, before cooling season
Replace the filter, flush the condensate drain with vinegar, clear leaves and pollen from the condenser, straighten bent fins, and book a coil clean. Do it in April, not in the first hot week when the queue is two weeks long.
Summer
Change the filter monthly in heavy use. Keep two feet clear around the condenser. Check the condensate pan for standing water, which is the first sign of a blocked line and a ceiling stain waiting to happen.
Autumn, before heating season
Test the heat on a mild day so a failure is inconvenient rather than an emergency. Clear the flue, confirm the carbon monoxide detector works, and have the heat exchanger inspected on any furnace over ten years old.
Winter
Keep the filter clean and the vents unobstructed. Never run a gas furnace with a cracked heat exchanger. If the outdoor unit ices in heating mode, that is a defrost fault, not weather.
What to leave to a technician
Refrigerant charge, capacitor and contactor replacement, heat exchanger inspection, and anything involving the gas line. Those need gauges and, in some cases, a license.
Frequently asked questions
How often should filters be changed?
Monthly in heavy use, and never less than every three months.
Does a maintenance plan pay for itself?
Sometimes. It buys priority scheduling more than parts, which is the real value in a heat wave.
How long does a furnace last?
Fifteen to twenty years with annual service. Half that without.
Should I cover the condenser in winter?
A breathable cover only. A sealed one traps moisture.