Heat pump maintenance checklist for Massachusetts winters

Massachusetts is one of the colder places heat pumps now heat. Cold-climate models are built for it: Mass Save says some cold climate heat pump models have been tested to produce heat at outdoor temperatures as low as -30°F Mass Save. But a unit buried in snow, a dirty filter or a blocked drain can wipe out that ability. This is the short list that matters.

When to do what

Indoor checklist

• Filters. Changing filters regularly is part of keeping a heat pump running well U.S. DOE. See how to clean them.
• Louvers and front panel. Wipe with a damp cloth. Keep furniture and curtains from blocking the airflow.
• Thermostat or remote. Check mode, setpoint and schedule. Big overnight setbacks make some systems work hard in the morning. See the cold weather guide.
• Smell, noise, dripping. A new smell or drip is a sign to act early. Smell guide, leak guide.

Outdoor unit: snow, ice and clearance

• Snow. When there is a significant snowfall, keep the outdoor unit clear of snow and ice NYSERDA. Brush it off by hand or with a soft broom. Do not use a shovel on the coil.
• Plants and debris. Trim shrubs back to at least two feet from the unit Trane. Pull leaves out of the grille in the fall.
• Under the unit. A wall-bracket or stand keeps it above drifts. If drifts reach the base, shovel a path.
• Roof runoff. Do not let eave drip or roof snow fall onto the unit. A snow guard or an angled shield is a job for the installer.
• Do not chip ice off the coil. The fins are thin aluminium and bend and puncture easily. Let the defrost cycle do it.

Defrost: what is normal

In cold, damp weather a heat pump's outdoor coil frosts, and the unit runs a defrost cycle to melt it. New York State's heat pump guide puts it simply: during winter months it is normal for outdoor units to get icy on the coils NY HCR. Trane says the steam you may see rising from the unit is the ice melting and evaporating, and is perfectly normal Trane.

Call someone if the unit seems to defrost constantly or if the defrost cycles last longer and longer with frost and ice starting to cover the unit Trane.

Drains, codes and what you can ignore

• Drain outlet. The hose end should hang free and drain away from the house. In winter keep it above the snow line and out of ice. A blocked hose can back up into the head.
• Error codes. Mitsubishi, Fujitsu, Daikin and other brands report faults through blinking indicator lights on the indoor head or a code on the remote. The meaning differs by brand and model, so use your manual. Write down the pattern or take a photo, then switch the system off and back on once. If the code returns, call, and tell the technician the pattern. Do not keep resetting the breaker.
• Refrigerant and electrical. Not owner jobs. Leave line sets, panel covers and disconnect boxes alone.
• Snow guard and bracket. If the unit has shifted, tilted or is vibrating, call the installer.

When to call a technician

• The unit runs but the house does not warm up, and filters and the outdoor unit are clear. See not heating well.
• Ice covers the whole unit or defrost seems constant.
• A fault code that returns after one reset.
• Water inside, a burning smell, grinding or a loud outdoor fan.
• It has been more than a year or two since a professional looked at it. Ask about a heating tune-up.

If you are still deciding on a system, see how heat pumps work in Massachusetts and the rebate calculator. The Mass Save rebate drops on January 1, 2027, see the 2027 change.