HVAC Maintenance Checklist: Monthly, Seasonal and Yearly Tasks (and Tune-Up Cost)

• Monthly: check the air filter and replace it when dirty (most 1-inch filters need a change every 1 to 3 months). Make sure supply and return vents are not blocked.
• Each season: keep at least 2 feet of clear space around the outdoor unit, rinse debris from the condenser, check the condensate drain, and test the thermostat.
• Every year: schedule a professional tune-up for each system (cooling in spring, heating in fall). Heat pumps need it for both modes.
• Test detectors twice a year: carbon monoxide and smoke alarms, especially with gas or oil heat.
• Leave to pros: refrigerant checks, electrical testing, evaporator coil cleaning, gas burner and heat exchanger inspection.

1. Check the filter. Hold it up to light. If you cannot see through it, replace it. The U.S. Department of Energy says replacing a dirty filter can cut air conditioner energy use by about 5 to 15 percent.
2. Clear vents and returns. Do not block them with furniture or rugs.
3. Look at the outdoor unit. Check for debris, leaves and anything stacked against it.
4. Listen and smell. New grinding, squealing, or musty or burning smells deserve attention.

MERV (Minimum Efficiency Reporting Value) rates how well a filter catches particles, from 1 to 16 for homes. For most homes, MERV 8 to 13 is a good balance. Higher MERV filters catch more fine dust but restrict airflow more, and a filter too restrictive for your blower can reduce airflow, freeze the evaporator coil or overheat the furnace. Check your equipment manual or ask your technician what MERV your system can handle. Check the size printed on the filter edge (for example 16x25x1) and the arrow showing airflow direction. Thicker 4- or 5-inch media filters last longer, often 6 to 12 months. See also the EPA indoor air quality resources.

Spring (before cooling season)

• Remove leaves and debris and trim plants to keep about 2 feet of clearance around the condenser, per ENERGY STAR and DOE guidance.
• With power off at the disconnect, gently rinse the outdoor coil fins from the inside out with a garden hose. No pressure washer; bent fins reduce airflow.
• Flush the condensate drain line (see below) and check that the drain pan is dry.
• Run the AC for a few minutes and confirm cold air comes out of the vents.

Fall (before heating season)

• Replace the filter before first use.
• Check that the area around the furnace is clear of stored items.
• Test carbon monoxide alarms and replace batteries.
• For gas furnaces, make sure flue pipes and vent terminations outdoors are clear of snow, nests and debris.

Winter

• Keep snow and ice off the outdoor heat pump or AC unit and the high-efficiency furnace vent pipes.

The condensate drain carries water that the evaporator coil pulls from the air. When it clogs with algae or slime, water backs up, and a float switch may shut the system off or water may overflow. Once or twice per cooling season, many manufacturers suggest pouring about a cup of distilled white vinegar into the access tee near the indoor unit. Check your manual, avoid bleach with metal parts, and never mix cleaners. A wet-dry vacuum on the outside end of the line can clear stubborn clogs. Persistent clogs or any water around the air handler are a reason to call a pro.

The outdoor coil can be rinsed by the homeowner as above. The indoor evaporator coil sits behind a panel in the air handler, and cleaning it requires opening the system, so leave it to a technician. A dirty coil lowers efficiency and can freeze up.

Cooling tune-up: check refrigerant pressures and charge, inspect electrical connections, test the capacitor and contactor, clean the condenser coil, check the blower, evaluate the evaporator coil, clear the condensate drain and test thermostat operation. Heating tune-up (gas): inspect the burners, ignition and flame sensor, heat exchanger, flue and venting, measure combustion and carbon monoxide, check the blower and test safety controls. A good technician measures and records readings and gives you a written report.

Typical cost: roughly $75 to $250 per visit for a single system, often less with a maintenance plan and more in high-cost areas or for dual-fuel and heat pump systems. Be cautious of a very low price that leads to an expensive upsell. Repair recommendations should be written, explained and priced. Ask for a second opinion on large repairs; see HVAC contractor quote second opinion.

Call a technician sooner if the system short cycles, blows warm air, ices up, leaks water, has rising energy bills, makes new noises or has uneven rooms. Our guides on AC not cooling, furnace short cycling and HVAC troubleshooting help you decide. If you smell gas, leave the home and call your gas utility; if a carbon monoxide alarm sounds, get everyone outside and call 911.

• ENERGY STAR: Heating and Cooling Maintenance Checklist
• U.S. EPA: Indoor Air Quality