Maintaining a heat pump isn’t complicated, but most homeowners skip the tasks that actually matter. Here’s what to do before heating season, what’s safe to handle yourself, and what’s worth leaving to a tech.
Change or Clean the Air Filter First
This one’s obvious, but the timing matters more than people realize. A clogged filter forces the blower to work harder, which strains the compressor and can trip the system on a low-pressure fault before you even figure out what happened. For most residential systems with standard 1-inch filters, they need attention every 1-3 months depending on household dust load and whether you have pets. Pull it out, hold it up to light. If you can’t see through it, swap it.
Some units use washable filters. Rinse them with water, let them dry completely before reinstalling. Putting a damp filter back in creates its own problems.
Clean the Outdoor Unit
Heat pumps move heat in both directions, so the outdoor unit is a heat exchanger in both heating and cooling mode. Debris that’s fine in summer (leaves, cottonwood fluff, dried grass clippings) becomes a real problem in fall when you first switch to heating. The coil fins need airflow. Blocked fins mean the system works harder for the same output, and in cold weather that gap gets worse.
You can safely do this yourself. Shut the system off at the disconnect, then use a garden hose on a gentle setting to rinse the fins from the inside out if possible, or top-down. Don’t use a pressure washer. The fins are thin aluminum and bend easily. Clear any debris from around the unit, and make sure clearance around all sides meets your unit’s installation manual spec (varies by manufacturer, typically 12-24 inches on sides).
One thing people forget: if you covered the outdoor unit over summer, remove the cover before turning it on. Running a heat pump with a cover on it will damage the compressor quickly.
Check Refrigerant Line Insulation
The suction line (the larger, insulated copper line running into the house) should have continuous foam insulation along its length. Over time that insulation cracks, splits, or gets eaten by squirrels. Damaged insulation causes energy loss and can lead to moisture problems around line sets that run through conditioned space.
Look at the visible sections. If the foam is cracked or missing in spots, it’s an easy fix: foam pipe insulation from a hardware store, cut to length and taped. Note that most hardware store foam isn’t UV-rated for outdoor runs, so wrap any outdoor sections with UV-resistant line set tape. If you’re not sure which line is which, or the lines go through walls you can’t access, this is something to point out to your tech during the annual visit.
Test Heating Mode Before You Need It
Don’t wait for the first cold night to find out the reversing valve is sticking. Switch to heating mode on a mild day in September or October. Run it for 15-20 minutes. You should feel warm air from the vents within a few minutes. If it blows cold, trips a fault, or you hear a loud clunking noise during mode switch, that’s worth addressing before you actually need heat.
The reversing valve is the component that switches the refrigerant flow direction. When they start failing, you’ll often get intermittent behavior first: works sometimes, doesn’t others, or the outdoor unit runs normally but the air at the register is room temperature. This is a repair job, not a DIY item.
Check the Condensate Drain
In heating mode, condensation forms on the outdoor coil and drains to the ground normally. But if your system has an indoor air handler, check that the drain line isn’t blocked from the previous cooling season. A blocked drain from standing water or debris can back up into the air handler if cooling season left residue in the pan. Clear it with a wet/dry vac on the drain outlet, or flush it with a small amount of water to confirm it flows freely.
Inspect the Thermostat Settings
Before heating season, verify the thermostat is actually configured for heat pump operation, not conventional heating. On systems with a backup electric strip heater (called auxiliary or emergency heat), the thermostat needs to know it’s controlling a heat pump so it manages the staging correctly. Running a heat pump in “emergency heat” mode all winter is an expensive mistake. It means the strips are doing all the work and the compressor isn’t running at all.
If you have a smart thermostat that was installed by someone else, it’s worth checking that “heat pump” was selected during setup, and that the auxiliary heat threshold is set reasonably (typically kicks in when outdoor temps drop below 35-40°F, which is the general balance point for most standard heat pumps).
What a Tech Checks That You Can’t
Annual professional maintenance covers things the homeowner can’t safely do: checking refrigerant charge and looking for leaks, testing starting capacitors and contactors, measuring amperage draws to catch components that are wearing down before they fail, and inspecting electrical connections that corrode over time. Capacitors are high-voltage components and should only be tested by a trained tech. An experienced tech with a proper capacitance meter can catch a capacitor that’s reading outside its rated spec before it causes a no-start failure.
If the system is more than 5 years old and hasn’t been serviced in a while, a refrigerant check is worth doing. Low refrigerant doesn’t mean the system is fine with slightly less, it means there’s a leak somewhere, and the system efficiency drops sharply before you notice it in the thermostat readings.
When to Call
If you’ve done the homeowner tasks and the system still isn’t performing right, heating mode is inconsistent, you hear grinding or chattering from the outdoor unit, or the indoor unit is short-cycling, those are signs the system needs a diagnosis, not just a filter swap.
I run Adrium Service in the Tri-Valley and East Bay. We service heat pumps alongside the full range of HVAC and appliance work. If your system needs a pre-season check or something’s clearly off, you can book at adriumservice.com.