Heating and cooling care: filters, tune-ups and warning signs

Get to know the system you have

Start by figuring out what’s in your house. Common setups include a gas or electric furnace paired with a central air conditioner, a heat pump that handles both heating and cooling, a boiler with radiators, or ductless units mounted high on a wall. Each has its own care routine. Look for the data plate on the indoor and outdoor units and note the model, serial number and fuel type. The build date is often hidden inside the serial number; the maker’s documentation or a technician can translate it. Keep the manual, or download a copy, and store it with your home records.

• Find every filter

  Some homes keep the filter in a slot next to the furnace, others behind a big grille on a hallway wall or ceiling, and a few use both. Check every spot.

• Note the thermostat type

  Write down whether your thermostat is manual, programmable or connected to your home network. It affects how you schedule temperatures and what a technician may ask about.

• Keep equipment areas clear

  Boxes, laundry and paint cans don’t belong beside a furnace or air handler. Give the equipment room to breathe and give a technician room to work.

Change the filter on a real schedule

The filter is the easiest thing you can do for your system, and the easiest to forget. A clogged filter makes the blower work harder, can reduce airflow across the coil and lets dust settle where it shouldn’t. Check it monthly at first. Tilt it toward a window or a lamp; when the pleats look gray and light barely passes through, swap it out. Houses with pets, allergies, remodeling dust or long heating and cooling seasons often need changes more often. Jot the install date on the new filter’s cardboard frame so next month’s check isn’t a guess.

• Follow the airflow arrow

  Every filter has an arrow printed on the frame. Point it toward the furnace or air handler, away from the return duct it pulls air from.

• Buy the exact size

  The size is printed on the frame of the old filter. A filter that’s too small lets air sneak around the edges and skip filtering entirely.

• Ask before going denser

  Filters with higher efficiency ratings trap finer particles but can restrict airflow on some systems. Ask a technician what your equipment can handle before you switch.

Keep the outdoor unit breathing

Your air conditioner or heat pump has an outdoor unit that needs open space to move heat. Keep shrubs trimmed back, rake leaves away from the base and never stack firewood or bins against it. A couple of feet of clearance on every side is a common rule of thumb, though your manual may ask for more. With the system switched off at the thermostat, you can gently rinse dust and cottonwood off the fins with a garden hose. Skip the pressure washer, which can flatten the thin metal fins. In winter, keep snow and ice from burying a heat pump.

• Check that it’s level

  An outdoor unit resting on a sinking pad can strain its refrigerant lines. If the pad tilts noticeably, mention it at your next tune-up.

• Leave covers to the manual

  Some manufacturers advise against wrapping an outdoor unit in winter, since trapped moisture invites rust and rodents. Follow the manual for your specific model.

Watch the condensate drain and the vents

Air conditioners and high efficiency furnaces pull water out of the air, and that water has to go somewhere. Find the small pipe leaving the indoor unit and follow it to a floor drain, a pump or the outside. If you see standing water in the drain pan or a damp spot under the unit, the line may be clogged. Some manuals describe a simple way to flush the line; follow those steps only if they’re written for your equipment. Inside the house, keep supply and return vents open and clear of furniture and rugs, and vacuum dust off the grilles now and then.

• Don’t close off rooms

  Shutting vents in unused rooms can raise pressure in the ducts and reduce airflow. Ask a technician before closing off parts of the house.

• Listen for the pump

  If your system uses a condensate pump, get to know its normal hum. A pump that runs nonstop or stays silent while water pools needs attention.

Use the thermostat with a light touch

Steady settings are easier on equipment than big swings. If you use a schedule, keep the changes moderate, especially with a heat pump, because a large jump in temperature can call on backup electric heat. Replace thermostat batteries when the low battery signal appears or once a year, whichever comes first. Keep lamps, televisions and direct sun away from the thermostat, since extra heat nearby fools it. If rooms feel uneven, note which ones and at what time of day. That record is far more useful to a technician than a general complaint that the house never feels right.

• Mind the backup heat

  Many heat pump thermostats show when auxiliary or emergency heat is running. If it stays on during mild weather, have a technician check the system.

Book a seasonal tune-up

Homeowner care keeps the basics in order. A tune-up covers what you can’t safely reach. Schedule cooling service in spring and heating service in fall, before technicians are booked solid. A typical visit may include checking electrical connections and controls, measuring temperatures and airflow, cleaning or inspecting coils, testing safety switches and, for fuel-burning equipment, inspecting burners, the flue and the heat exchanger. On a cooling visit, a certified technician may also check the refrigerant charge. Checklists differ between companies, so ask what’s included before the visit.

• Ask for the checklist

  A reputable company should be able to tell you what the visit covers. Compare that list with what your equipment manual recommends.

• Get notes in writing

  Ask for a written summary of what was checked, any readings taken and any repairs suggested, and keep it in your home log for next season.

• Slow down on big repairs

  If a technician recommends a major repair, ask to see the problem, get the quote in writing and take time for a second opinion when it isn’t an emergency.

Learn the warning signs

Your system will often hint at trouble before it quits. Pay attention when something changes: a new noise, a new smell, rooms that won’t reach the set temperature, or a system that turns on and off every few minutes. A faint dusty smell on the first cold morning of fall is common as the burners heat up, but it should fade quickly. A persistent burning, electrical or chemical smell should not. Rising energy bills with no change in weather or habits can also point to a problem. When in doubt, turn the system off and call a licensed technician.

• Ice on the lines

  Frost or ice on the copper lines or the indoor coil usually signals an airflow or refrigerant problem. Turn cooling off and call for service.

• Short cycling

  A system that starts and stops repeatedly within a few minutes wears parts quickly. It can come from a dirty filter, a thermostat issue or something more serious.

• Water where it shouldn’t be

  Puddles near the indoor unit, a sweating duct or water stains on a ceiling below an attic air handler all deserve a quick call to a pro.

• Grinding, squealing or banging

  Sharp mechanical noises often mean a motor, belt or fan is in trouble. Running the system anyway can turn a small repair into a bigger one.

Treat gas and carbon monoxide warnings as emergencies

Some problems aren’t a scheduling question. Utilities add an odor to natural gas that many people compare to rotten eggs. If you notice it, move everyone outdoors, then phone your gas company or emergency services once you’re well away from the house. Don’t use light switches, phones or anything that could spark while you’re still indoors. If a carbon monoxide alarm sounds, get everyone into fresh air and call emergency services. Install carbon monoxide alarms as the manufacturer directs, typically near sleeping areas and on each level of the home. Placement requirements are set locally and differ between states and cities, so look up the rules where you live.