How to Protect Your Heat Pump During a Sudden Freeze in Charleston

Your phone just buzzed with a freeze warning. Charleston's dropping into the 20s—maybe even the teens—and staying there for days.

Maybe you're in Mount Pleasant watching the weather radar. Maybe you're in Summerville wondering if your heat pump can handle multiple nights below freezing. Whether it's happening right now or coming next month, here's what you need to know.

Here's the thing about Lowcountry HVAC systems: They're built for August, not January. Your heat pump is a workhorse when it's 95 degrees and sticky. It's a different game when the temperature drops below freezing.

The stakes? When your heat pump ices over and you ignore it, you're looking at emergency service calls, possible compressor damage, and repair bills that run into the thousands. One bad freeze can turn into one of those insurance claims that averages $15,400 when pipes burst and systems fail.

Most Charleston freezes won't kill your system. But they'll test it. If something's already weak—low refrigerant, dirty coils, a failing defrost sensor—a cold snap will find it.

Here's what works. Nothing fancy. Just what to do right now to keep your system running when everyone else is scrambling for emergency service.

Your System Wasn't Built for This

Heat pumps work backwards in winter. Instead of pushing hot air outside like your AC does in summer, they pull heat from the outside air and move it inside. Even when it's cold out, there's still heat in the air. Your system knows how to find it.

The problem? The refrigerant running through those outdoor coils sits about 10 degrees colder than the air temperature. When it's 32° outside, your coils are at 22°. Ice forms fast.

Why do Charleston systems get caught? We use them 10 months a year for cooling. Heating mode barely gets a workout. By the time January rolls around, those defrost cycles haven't been tested since last winter. If something's going to fail, it'll fail when you need it most.

Multi-day freezes are tougher on systems than single cold nights. Your heat pump can handle one night in the 20s. Two or three nights in a row? That's when weak spots show up.

We got a call from a house in Summerville last January. The heat pump had been struggling for a week—homeowner kept cranking the thermostat up thinking it would catch up. By the time we arrived, the outdoor coils were covered in ice and the compressor was working overtime trying to compensate.

The reversing valve was stuck. The repair wasn't cheap.

Could've been a simple service call if we'd caught it earlier.

The Heat Pump Freeze Prep Checklist

Here's what to do before the temperature drops—or right now if you're already in it.

Step 1: Clear the Area (15 Minutes)

Walk outside. Look at your unit. Pull back the leaves. Charleston's got plenty—live oak, magnolia, palmetto. They pile up fast. Your outdoor unit needs 2 to 3 feet of clearance on all sides to breathe.

While you're out there, check the gutters. If one's dripping onto your unit, that water's going to freeze right where you don't want it. Fix it now or tape a piece of plastic to redirect the flow.

Step 2: Swap Your Filter (10 Minutes)

Dirty filters equal restricted airflow. Restricted airflow equals frozen coils. Pull your filter out. Hold it up to the light. If you can't see through it, replace it. Keep spares in the garage. You'll thank yourself later.

This isn't just freeze prep. Clean filters prevent 70% of the breakdowns we see in Charleston homes year-round. It's the easiest thing you can do, and most people skip it.

We've pulled filters out of systems that looked like they'd been vacuuming the Spanish moss off the live oaks. The system's working twice as hard as it should. Simple fix.

Step 3: Test Your Heat (20 Minutes)

Don't wait for a freeze to find out your heat doesn't work.

Turn it on now. Let it run for 20 minutes. Walk outside and watch the outdoor unit. Listen for sounds that don't belong—grinding, clicking, squealing. If something sounds wrong, it probably is.

Light frost on the coils? That's normal. Thick ice building up within minutes? That's the system talking to you.

Here's what we hear on most emergency calls during a freeze: "I haven't turned the heat on since March. Turned it on when the temperature dropped and nothing happened."

Test it now. Not later.

Step 4: Set Your Smart Thermostat (5 Minutes)

Pick a temperature. Leave it there. 68° is the sweet spot for most homes.

Don't crank it up and down trying to "help" the system. Heat pumps hate that. They're designed to run steady, not chase a moving target.

If you've got a smart thermostat, now's when it earns its keep. It adjusts for you automatically and sends alerts if something's struggling. That 8% savings on your heating bill doesn't hurt either.

We installed one for a family on Daniel Island last fall. Two months later, they got an alert at 2 am that their system was working too hard. They called us first thing. We caught a failing motor before it quit completely. Saved them from waking up in a cold house.

Don't have one yet? We can walk you through options that make sense for Charleston homes. Smart thermostats pay for themselves faster than most people think.

Step 5: Protect the Outdoor Unit (10 Minutes)

Do NOT cover your heat pump.

Sounds backwards, but here's why: Covers trap moisture. Moisture freezes. Ice expands. Now you've made the problem worse.

Heat pumps are built to run in cold weather. That outdoor unit isn't delicate. Leave it alone. If we get one of those rare Charleston snowfalls (it happens), brush the snow off gently with a broom.

Don't use a shovel. Don't chip ice with a screwdriver or hammer. Those coils and fins bend easy, and you can't un-bend them.

When Ice Takes Over

Sometimes you do everything right and the system still freezes. This happens when the temperature drops fast or stays below freezing longer than usual.

Here's how to spot real trouble: The entire unit is covered in thick ice—not just frost—for 3 hours or more. The system's running but no heat's coming out. Or it's making noises you've never heard before.

What to do:

1. Turn the system off. Don't let it keep running and damage itself.

2. Switch to emergency heat. Most thermostats have an "EM Heat" setting. It's less efficient, but it'll keep you warm while the outdoor unit thaws.

3. Thaw it slowly. Use a garden hose with warm water—not boiling. Let it thaw completely. This takes 2 to 3 hours.

4. Watch for repeat problems. If the ice comes right back or the system won't heat after thawing, call for service.

   
   

Real talk: Emergency calls during a freeze cost 50 to 100% more than a regular visit. And you're waiting while everyone else is calling too. Response times stretch during cold snaps. If you can avoid the emergency, avoid it.

A Little Maintenance Beats a Big Repair

One freeze prep checklist isn't enough. Charleston's getting these cold snaps more often now. January. February. Even late November some years.

You can do the 24-hour drill every time the weather dips. Or you can get ahead of it. Here's what a maintenance plan actually does: It catches problems before they strand you. A failing motor. A stuck reversing valve. Low refrigerant. All things we find during routine checkups—stuff that would've quit during the next freeze.

Preventive maintenance cuts system failures by 95%. It keeps your heat pump running 15 to 20 years instead of limping through 10. Studies show it delivers a 545% return on what you spend. Not because maintenance is magic. Because it finds the small stuff before it becomes expensive stuff.

You also get priority service. When the temperature drops and the phones start ringing, maintenance customers move to the front of the line. No waiting.

Smart thermostats work as backup brains for your system. They monitor 24/7. They alert you if something's not right—temperature drops, unit's struggling, system's running longer than it should. You're not babysitting it. It's watching itself.

We installed them in homes from North Charleston to Goose Creek. Every single customer says the same thing: "Wish I'd done this sooner."

The Next Freeze Is Coming

Quick recap:

Clear debris around the unit. Swap the filter. Test your heat before you need it. Set your thermostat and leave it. Don't cover the outdoor unit.

That's the checklist. It works whether you've got a day to prepare or you're already in the middle of a cold snap.

But Charleston's not done with winter. Another freeze is on the way—maybe next week, maybe next March. You can run this drill every time. Or you can set up a system that handles it for you.

We've been fixing HVAC in Charleston since 2006. We've seen every freeze, every cold snap, every December and January panic call. We know what breaks and we know how to keep it from breaking.

If your system's acting up, or you just want peace of mind before the next freeze warning, give us a call.

We're here.