Performing regular maintenance on your heating- ventilation-air conditioning system (HVAC) is the best way of keeping the unit running at top efficiency and the lowest expense. Regular HVAC maintenance also helps you get the longest life possible out of your investment and gives you assurance the unit will be working when you need it.

Some kinds of HVAC maintenance should be left to a qualified and reputable heating and cooling company. There are also some maintenance tasks homeowners can easily do themselves. Whoever does the job, staying on task with HVAC maintenance is the best way of staying comfortable in all seasons and saving on energy costs at the same time.

For systems that do both heating and cooling, maintenance tasks are needed in the spring and fall. Systems that cool only need maintenance annually at the start of the hot season. Stand-alone furnaces need a maintenance check once a year at the start of the heating season. Each type of unit needs somewhat different attention, but these are the main points of HVAC maintenance for most systems.

  • Replace filters regularly, and keep a supply of filters on hand. Newer, pleated filters are made to have an electrostatic charge which attracts dust particles and even bacteria and mold spoors. Replace the filter every three months, but monitor it monthly and replace it sooner if it looks dirty. Homes with pets need more frequent filter replacement.
  • At least monthly, remove debris that has fallen onto the unit. Leaves, branches, dust, and pollen block airflow and reduce the efficiency of HVAC systems. Check that lawn mowers and weed eaters do not throw cut grass onto the sides of the HVAC unit. Make sure there is at least two feet of clear space around the entire unit at all times.
  • Check that the HVAC unit is sitting firmly on level ground. If it has shifted, contact a heating and cooling company for repairs.
  • During the summer, the water to the furnace humidifier can be shut off to prevent leaks.

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In the fall, the wick filter on the humidifier should be replaced and the thermostat adjusted to thirty-five percent humidity before the water is turned back on.

  • Once a year, pour one cup of bleach mixed into a quart of water into the AC condensate drain to kill algae and mold.
  • Inspect the refrigerant levels and lines. Add refrigerant, if needed, and repair any leaks in lines before using the unit.
  • Clean out dust, spider webs, and other debris from inside the unit to prevent electrical problems.
  • Inspect the drain pans and make sure the drains are working properly.
  • Inspect and clean the coil, fan motor, and fan blades, blower housing, and blower motor. Older models often need occasional lubrication.
  • Inspect the control unit wiring and connections.
  • Inspect the compressor and clean or repair as needed.
  • Clean the condensate drain and pan.
  • Check for gas leaks on furnaces.
  • Adjust the burner as needed.
  • Check flues and duct work for damage, dislocation, and corrosion and repair as needed. Check ducts for airflow leaks while the unit is running.
  • Check heat pump and AC refrigerant charge levels annually.
  • Monitor outdoor and indoor dry bulb temperature settings.
  • Check gas pressure to furnace and adjust if necessary.
  • Check that vents are adjusted properly for airflow.
  • Monitor the unit per any other manufacturer recommended specifications.


When the system is being turned on for the first time in the season, listen for abnormal sounds and check for unusual odors. It is a good idea to do a check like this a few weeks before you are likely to need heat or air conditioning. That way, there is time for any needed repairs or HVAC maintenance to be done by a HVAC specialist before the weather changes.

When looking for a reliable company to maintain your HVAC system, ask them for a check list of everything they inspect on each service call and make sure they cover the points listed above.