Seasonal HVAC Maintenance Checklist for DMV Homes

Every month or two: the filter

The single most useful thing a homeowner can do. A clogged filter starves the system of air, freezes the coil in summer, overheats the furnace in winter and shortens the life of the blower motor. Pleated filters in a house with pets or construction dust need changing more often than the box says.

Write the date on the edge of the new filter. If you are not sure which filter to use, the filter FAQ covers it.

Spring, before the first hot week

• Clear leaves, grass clippings and mulch from around the outdoor condenser; it needs air on all sides
• Rinse the condenser coil from the inside out with a hose, with the power off, if the fins are visibly dirty
• Run the system on cooling for ten minutes on a mild day and check that cold air arrives at every register
• Check the condensate drain line where it exits; a slow drip on a cooling day is normal, no water at all on a humid day is not
• Pour a cup of water into the condensate pan to be sure the drain and the float switch work
• Set the thermostat schedule for summer

What the technician does on the spring visit: refrigerant pressures and temperatures at the equipment, capacitor and contactor readings, blower amperage, coil condition, condensate line cleared, and the readings written down so next year has something to compare against.

Fall, before the first cold night

• Switch the thermostat to heat on a mild day and listen to the start-up; a bang, a delayed ignition or a burning smell that does not clear in a few minutes is a call
• Check that every supply register is open and nothing is stacked on top of the return grilles
• Replace the batteries in the thermostat and the carbon monoxide detectors
• Clear the area around the furnace; it needs combustion air and nothing stored against it
• On a heat pump, clear the outdoor unit and make sure it has room to drain during defrost
• Set the thermostat schedule for winter

What the technician does on the fall visit: heat exchanger inspection, flame sensor and ignitor check, gas pressure, combustion readings, blower and inducer motor condition, condensate on a high efficiency furnace, and on a heat pump the defrost cycle and the backup heat.

What belongs to a technician

• Anything involving refrigerant: it is federally regulated and takes an EPA certified technician
• Gas connections and gas pressure
• The heat exchanger: a cracked one is a carbon monoxide risk, and we shut it down and show you why
• Electrical readings at the capacitor, contactor and motors
• The indoor evaporator coil, which is inside the air handler and easy to damage

Signs to call before the season starts

• The system ran noticeably longer last season to hold the same temperature
• Ice on the copper lines or the indoor coil at any point last summer
• One room that fell behind the rest of the house
• A heat pump that ran the backup strips most of last winter, which shows up on the electric bill
• Water around the indoor unit or a stain on the ceiling below it
• A furnace past fifteen years that has not been looked at in a while

How often a system actually needs a visit, and what a plan covers, is in the guide on the maintenance schedule.