A heat pump doesn’t “create” heat like a furnace—it moves heat from outside to inside. Even on a cold day, there’s still heat energy in the outdoor air that the system can pull in and compress to warm your home.
But when a true arctic blast hits and temps dive into the 20s or teens, a few things can happen:
- Efficiency drops: Your heat pump has to work much harder to find usable heat outside. It runs longer and uses more electricity.
- Heating capacity goes down: As it gets colder, your heat pump can’t produce as much heat as it can at milder temperatures.
- Defrost cycles increase: Moist PNW air + freezing temperatures = frost and ice on the outdoor unit. The heat pump switches into defrost mode more often to melt that ice.
- Backup heat may kick in: Many systems have electric heat strips or a furnace backup that turns on when it’s too cold or the heat pump can’t keep up.
None of this is “bad” or “broken”—it’s just how heat pumps behave in severe cold. But if your system isn’t maintained, sized properly, or set up for our climate, a cold snap can expose every weakness at once.
How PNW Arctic Blasts Stress Your Heat Pump
Our region has a specific kind of cold:
- High humidity that turns into frost and ice quickly
- Fraser outflow and east winds that bring bone-chilling air through gaps and leaks
- Freezing rain and sleet that can encase outdoor units in ice
- Power flickers or outages that can disrupt normal operation
During these events, you might notice:
- Your heat pump running almost non-stop
- Cooler air coming from the vents than you’re used to
- Steam coming off the outdoor unit during defrost cycles
- Higher electric bills for that period
- The system switching into auxiliary or emergency heat
Some of these are normal; others are a warning sign. The key is to get ahead of problems before the cold arrives.
Pre-Cold-Snap Checklist: What to Do Before Temps Drop
Ideally, you want to prep your heat pump in late fall—well before the first hard freeze. Here’s a practical checklist you can use or turn into a printable for your customers.
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Clear and Inspect the Outdoor Unit
Your outdoor unit needs space and air to breathe.
- Remove leaves, pine needles, and yard debris within at least 2–3 feet of the unit
- Trim back shrubs and branches
- Make sure the top and sides aren’t blocked by stacked items, firewood, or tarps
- Check that the unit is sitting level and not sinking into soft soil or mud
In a cold snap, poor airflow + ice buildup is a recipe for trouble.
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Protect Against Ice and Roof Runoff
One PNW-specific issue: gutters and rooflines dumping water or melting snow directly onto the heat pump.
- Check gutters and downspouts above the unit
- Redirect downspouts so they don’t drain onto or right next to the heat pump
- Make sure there’s no constant drip above the equipment that can turn into a block of ice
If needed, consider a properly designed protective cover or awning above the unit (installed with enough clearance for airflow and service).
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Replace or Clean Air Filters
A dirty air filter makes your whole system work harder—especially when it’s already fighting the cold.
- Replace disposable filters or thoroughly clean washable ones
- Make a note on your calendar to check filters monthly through winter
Good airflow = better comfort and fewer breakdowns.
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Test Your Backup Heat
Many PNW homes with heat pumps have:
- Electric auxiliary heat strips, or
- A dual-fuel setup with a gas furnace as backup
Before a cold snap, test that backup heat:
- Switch to emergency heat on your thermostat (if you have that setting) and make sure warm air is coming from the vents
- Listen for unusual noises and check for odd smells
If backup heat doesn’t seem to work, don’t wait until the coldest night of the year to find out. Call a pro to diagnose it.
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Schedule a Professional Heat Pump Tune-Up
A preseason tune-up helps catch little problems before they become big winter headaches. A technician can:
- Check refrigerant levels and look for leaks
- Inspect electrical connections and safety controls
- Verify proper defrost operation
- Inspect the outdoor coil and fan
- Confirm that the system is performing within specs
This is especially important if your heat pump:
- Is more than 8–10 years old
- Struggled to keep up during last year’s cold snaps
- Has had frequent error codes or shutdowns
What to Do During a PNW Cold Snap
Once the arctic air arrives, your priority is to help your system do its job without over-stressing it.
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Don’t Constantly Crank the Thermostat
Set a comfortable but realistic temperature—often 68–70°F—and leave it there.
- Avoid big setbacks (like dropping to 60°F at night and up to 72°F in the morning). Your heat pump will struggle to make up the difference in extreme cold.
- Small adjustments (1–2 degrees) are fine, but constant big swings can force the backup heat to run more, driving up your bill.
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Keep an Eye on the Outdoor Unit
During a cold snap:
- It’s normal to see steam coming off the outdoor unit during defrost cycles. That’s just the system melting ice.
- It’s not normal for the unit to be buried in snow or encased in solid ice.
If you see heavy snow or ice:
- Gently brush off snow with a soft broom
- Clear space around the unit for airflow
- Do not chip away ice with a shovel or sharp object—it can damage the coils and fins.
If the unit is encased in thick ice or making strange noises (like grinding or metal-on-metal), turn it off and call a pro.
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Use Curtains and Shades Strategically
Help your heat pump by reducing heat loss:
- Open curtains on sunny sides of the home during the day
- Close them at night to add an extra layer of insulation
- Close blinds in rooms you’re not using to cut drafts around windows
Small steps add up to less run-time and better comfort.
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Be Prepared for Power Flickers
If the power goes out or flickers:
- Give the system a few minutes after power returns before you start adjusting the thermostat
- If the outdoor unit looks frozen solid or is making loud, unusual sounds after the power comes back, shut it down and call for service
After the Cold Snap: Quick Post-Storm Check
When the weather finally warms back up, take a few minutes to:
- Walk around the outdoor unit and make sure there’s no visible damage
- Listen for new rattling, grinding, or squealing sounds
- Look at your thermostat and note if the system is behaving normally again
If anything seems off—hot/cold spots, strange noises, or sudden spikes in your electric bill—schedule a post-cold-snap inspection.
Should You Consider a Cold-Climate Heat Pump?
If your home struggled through the last cold snap even after maintenance, it may be time to talk about upgrades. Today’s cold-climate heat pumps are designed to:
- Maintain strong heating capacity at much lower outdoor temperatures
- Run more efficiently in freezing conditions
- Pair well with smart thermostats and zoning systems
Other upgrades that can make a big difference:
- Sealing and insulating ductwork
- Adding insulation and air sealing in attics and crawlspaces
- Installing a dual-fuel setup (heat pump + furnace backup)
These changes not only help during arctic blasts but can also lower your energy bills year-round.
In Summary: Don’t Wait for the First Hard Freeze
PNW cold snaps don’t happen every week—but when they do, they expose every weak link in your heat pump system and your home’s envelope.
If you:
- Clear and protect your outdoor unit
- Keep filters clean and air flowing
- Test your backup heat
- Schedule a professional tune-up before winter
- Use smart thermostat habits during extreme cold
…your heat pump is far more likely to keep your home comfortable, even when the Fraser outflow winds are howling and the sidewalks are iced over.
Stay ahead of the next cold snap instead of scrambling when temps drop. If your heat pump is due for a checkup—or already struggling—call Energy Technologies at (206) 580-1151 or book your service online. Our HVAC team will inspect, tune, and prepare your system so your Pacific Northwest home stays comfortable, efficient, and worry-free all winter long.
