How often should you have your HVAC system serviced?

Short answer

Get an HVAC tune-up once or twice a year. A system that both heats and cools gets a visit in spring for the air conditioner and another in fall for the furnace. A heat pump, which does both jobs with the same equipment, still benefits from a visit before each season. A home with heating only or cooling only needs a single visit before that season starts. A tune-up takes a technician 60 to 120 minutes and costs $75 to $200 per visit.

Why it matters

A furnace or air conditioner is a machine with moving parts, electrical connections and, in a gas furnace, a flame. Each of those drifts out of adjustment a little every season. Belts stretch. Electrical contacts pit and loosen. Refrigerant charge creeps low through tiny leaks. A burner collects dust that shifts the flame.

None of that stops the system right away. It just makes it work harder, which costs you on every bill, and it builds toward a failure that lands on the hottest or coldest day of the year, when every technician in town is booked. A tune-up catches the loose wire or the low charge while it's still a small adjustment, and a system that isn't pushed past its limits reaches its full 15 to 20 year life instead of giving out early. Most manufacturers also tie their warranty to yearly service, so skipping it can cost you the coverage when a big part fails.

When to do it more often

A tune-up schedule is already tied to the seasons, so there's rarely a reason to add visits. The things that change the schedule are about which visits you need:

Both heating and cooling: twice a year, with the cooling visit in spring and the heating visit in fall.
A heat pump: twice a year, because the same unit runs through both seasons and has no off season to rest.
Heating only or cooling only: once a year, before that season.

If the system starts short cycling or making a new noise between visits, call rather than waiting for the next scheduled one.

What you need

Nothing. The technician brings the gauges, meters and cleaning supplies. What helps is a clear path to the indoor unit and the outdoor unit, a fresh filter so the airflow readings mean something, and a note of anything you've noticed, like a room that won't get cool or a smell when the furnace starts.

Steps at a glance

Book the visit before the season starts, when technicians still have open days.
Clear the space around the indoor unit and the outdoor unit.
The technician checks the thermostat, the electrical connections, the capacitors and the blower.
For cooling, they clean the coils, check the refrigerant charge and clear the condensate drain.
For heating, they inspect the heat exchanger and burners, test the igniter and check the flue.
They run the system through a full cycle and measure the temperature it produces.
Ask what they found and what they'd watch next season.

You're done when the system runs a full cycle without a fault and you have a written list of anything that needs attention.

Signs it's overdue

Weak airflow at the vents with a clean filter in place.
Short cycling: the system starts, runs briefly, and stops, over and over.
New noises, such as grinding, squealing or a bang when the furnace lights.
Rising energy bills that the weather doesn't explain.
Rooms that heat or cool unevenly compared with last year.

DIY or pro

This is a pro-only job. Checking refrigerant, testing a heat exchanger for cracks and measuring electrical loads all need instruments and training you don't have at home, and opening the refrigerant side of a system is restricted work. What you can do yourself is everything around the tune-up: changing the filter, keeping the outdoor unit clear, and flushing the condensate drain in summer. Those keep the system healthy between visits and make each visit shorter.

Expect to pay $75 to $200 for a visit. Many companies sell a yearly plan that covers both visits and gives priority scheduling in a breakdown, which is worth it if you'd otherwise forget to book.

Safety

Gas: a furnace tune-up includes a check of the heat exchanger and the flue. A cracked exchanger can leak carbon monoxide into the house, and a technician has the instruments to find it. If you ever smell gas near the furnace, leave the house and call the gas company before anyone works on it.
Electricity: the technician will shut off power at the disconnect before opening panels. Don't open the furnace or the outdoor unit's electrical panel yourself. Capacitors hold a charge after the power is off.

FAQ

Is an HVAC tune-up worth the money?

Yes, for any system you want to last. One prevented breakdown pays for years of visits, and the efficiency gains show up on every bill.

What does an HVAC tune-up include?

An inspection of the electrical parts, a coil cleaning, a refrigerant check, a drain line flush, a heat exchanger and burner inspection, and a full test run with temperature readings.

When is the best time to schedule it?

Spring for cooling and fall for heating, before the first hot or cold spell. Technicians fill their calendars once the weather turns.

Does a new system need a tune-up?

Yes, from its first year. The warranty usually requires it, and installation problems show up early.