The Ultimate HVAC Maintenance Checklist for Every Season

HVAC equipment lasts longer, runs more efficiently, and breaks down less often when you stay on top of routine maintenance. For a southern New Hampshire home, that means a seasonal rhythm: spring prep before cooling season, fall prep before heating season, with simple monthly homeowner tasks year-round in between. The total time investment is modest. The payoff in avoided emergency calls, lower bills, and longer equipment life is substantial.

Here is the complete seasonal HVAC checklist that works for most NH homes.

Monthly homeowner tasks (year-round)

• Check the air filter. Replace 1-inch filters at least every three months; media filters last six to twelve months. Pets and renovation work shorten the interval.
• Test smoke and CO detectors. Hit the test button. Replace batteries annually.
• Look around HVAC equipment for moisture, rust stains, scorching, or anything that does not look right.
• Listen during operation. Notice any new noises (squeaks, rattles, hissing, banging) that were not there before.

Spring tasks (March to May)

Before the first hot day

• Schedule a professional AC or heat pump tune-up. This is the most important spring item. Late March through May is ideal; demand climbs fast after Memorial Day.
• Replace the air filter if you have not in the last three months.
• Replace thermostat batteries (for battery-powered models).
• Clear the outdoor unit area of leaves, branches, and accumulated debris from winter. Keep at least two feet of clearance on all sides.
• Rinse the outdoor coil gently with a garden hose after disconnecting power at the outdoor disconnect.
• Verify the condensate drain is clear and the drain pan is intact.
• Test the AC by setting the thermostat below the current room temperature. Confirm cold air at the supply vents within 10 to 15 minutes.

After the first cooling test

• Note any unusual smells, sounds, or performance issues
• Confirm thermostat schedule is set for summer occupancy
• For smart thermostats, verify settings and update firmware if available

Summer tasks (June to August)

Ongoing

• Check filter monthly during heavy AC use
• Keep outdoor unit clear of grass clippings and pollen buildup
• Watch for ice on the indoor coil (visible through the access panel or as water dripping from the air handler). Ice indicates a real problem; turn the system off and call.
• Confirm humidity is reasonable (under 55 percent indoors). Sustained high humidity may indicate an oversized AC or another issue.

Mid-summer

• Rinse the outdoor coil again if it gets visibly dusty
• Note any decline in cooling capacity (system runs longer to reach setpoint, rooms drift warmer in the afternoon)

Fall tasks (September to November)

Before the first cold snap

• Schedule a professional heating system tune-up. Most important fall item. Late September through October is ideal.
• Replace the air filter
• Replace thermostat batteries
• Test CO detectors and replace batteries
• Test smoke detectors and replace batteries (especially important before fuel-burning equipment starts running daily)
• Clear leaves and debris from around the outdoor heat pump unit
• Verify the outdoor heat pump has 18 to 24 inches of clearance on all sides for winter snow buildup
• For oil systems: top off the oil tank if you are entering the season with the tank near the bottom
• For propane systems: sign up for automatic delivery if you are not already on it
• Check the area around the chimney or flue for any visible obstructions (animal nests, debris)

Drain and disconnect outdoor plumbing

• Disconnect garden hoses
• Drain and store hoses indoors
• Close indoor shut-off valves for outdoor hose bibbs (if you have them)
• Open the outdoor faucet briefly to drain the line

Reverse ceiling fans

Set ceiling fan direction to clockwise (looking up) at low speed during winter. This pulls warm air up and pushes it down along the walls, helping circulate heat without creating a draft.

Locate your main water shut-off

Every household member should know where it is and how to operate it before a winter pipe emergency.

Winter tasks (December to February)

Ongoing

• Check filter monthly during heating season
• Keep the heating system running even when away (no lower than 60°F)
• For heat pumps: keep the outdoor unit clear of snow and ice; maintain clearance
• For high-efficiency furnaces and boilers: confirm PVC vents are clear of snow after storms
• For propane tanks: watch the gauge during prolonged cold; keep above one-quarter full
• For oil tanks: same; keep above one-quarter to avoid drawing sediment from the bottom

During cold snaps

• Open cabinet doors under sinks on exterior walls
• Open interior doors for air circulation
• Let exterior-wall faucets drip slowly
• Avoid large thermostat setbacks even at night
• If you also use a wood or pellet stove, keep the central heating system running so all areas of the home stay protected

Annual professional service (when to schedule)

Heating system: late summer through fall

Boiler, furnace, or heat pump heating-side service. Combustion analysis, heat exchanger inspection, control testing, filter replacement.

Cooling system: spring

AC or heat pump cooling-side service. Coil cleaning, refrigerant verification, electrical inspection, capacitor testing.

Water heater: annually

Tank flush, T&P valve test, anode rod inspection (replacement every 3 to 5 years), or annual descaling for tankless units.

Generator: annually

Oil change, battery test, load test, fault code review.

Service contracts

For homeowners who prefer not to think about scheduling, many HVAC contractors offer service contracts that bundle annual maintenance, priority service in emergencies, and a discount on repair parts. For NH homes with multiple systems (boiler, AC, water heater, generator), a contract often pays for itself in service-call avoidance alone.

Schedule maintenance

If you want to set up a proactive maintenance schedule for your NH home, contact A.J. LeBlanc Heating. Serving New Hampshire families since 1928.

Frequently Asked Questions

How often should I schedule professional HVAC maintenance?

Once per year for each system. Heating system in fall, cooling system in spring, water heater in spring or fall, generator annually.

How often should I change my HVAC air filter?

Check 1-inch filters monthly; replace every three months. Media filters last six to twelve months. Pets and renovation work shorten the interval.

Do I really need annual maintenance?

For warranty coverage, yes (most major brands require it). For equipment longevity and operating cost, yes (most major failures we respond to had warning signs that would have been caught during routine service). For peace of mind, yes.

What is the difference between homeowner maintenance and professional service?

Homeowner tasks are visual inspections, filter changes, and clearing debris. Professional service covers combustion analysis, refrigerant checks, electrical testing, internal component cleaning, and any work requiring tools or training homeowners do not have.

How much does an annual tune-up cost?

Typically $150 to $300 in southern NH depending on the contractor and the system. Service plans that bundle multiple visits often cost less per visit.