# What happens to a heat pump in an ice storm or a power outage?

> What happens to a heat pump in a Memphis ice storm or power outage, how to protect it, when to use emergency heat, and what generators and dual fuel change.

URL: https://blufflinememphisheatpumps.com/guide/heat-pump-ice-storm-power-outage/

Learn

Ice on the unit, power out for a day, and what to do before, during and after. Plus how gas, strips and generators compare.

Last Updated: November 12, 2026

The short answer

In a power outage a heat pump stops, and so does a gas furnace, since it needs power for its blower and controls. In an ice storm the outdoor unit can ice over; if the fan is frozen, switch to emergency heat until it clears. A generator can run a furnace's blower easily, but strip heat needs a much larger one.

Key takeaways

- Both heat pumps and gas furnaces stop when the power goes out.
- Freezing rain can coat the top fan and cabinet; defrost can't clear ice on the outside.
- If the fan is frozen, use emergency heat and let the ice melt; don't chip at it.
- After power returns, expect a restart delay and a burst of backup heat.
- A small generator runs a gas furnace; strip heat needs a much larger one.

## Memphis gets ice, not snow

Memphis winters bring a few hard freezes and, every few years, freezing rain that coats trees, power lines and anything left outside. Ice storms are when outages and frozen outdoor units happen together.

[Bluffline Memphis Heat Pumps](https://blufflinememphisheatpumps.com/) gets asked what to expect in both, so here is the plan before, during and after.

### The short version

| Situation | What to do |
| --- | --- |
| Frost on the coil, steaming every hour or so | Nothing; that is normal defrost |
| Ice coating the top fan or cabinet | Switch to emergency heat; let it melt |
| Power out | Nothing runs; plan for warmth without heat |
| Power back on | Expect a short restart delay and some backup heat |
| Fan still frozen after power returns | Stay on emergency heat until it turns freely |

## Before the storm

A little preparation helps the outdoor unit come through.

### Check above the unit

Gutters that overflow, or roof edges without gutters, drip onto the unit. In freezing rain that water becomes a sheet of ice on the top fan. Clear the gutters in fall and add a downspout extension or diverter if water lands on the unit.

### Check below the unit

A raised pad lets meltwater drain away. A unit sitting low in a wet corner freezes into its own ice. If yours sits in a low spot, the [placement guide](https://blufflinememphisheatpumps.com/guide/outdoor-unit-placement-noise/) explains why raising or moving it at replacement time helps.

### Don’t cover it

A heat pump runs in winter. A cover blocks the airflow it needs and can trap moisture against the coil.

## During an ice storm

If freezing rain coats the outdoor unit, the normal defrost cycle can’t help: defrost warms the coil from the inside, but ice on the top fan and the cabinet stays.

### If the fan is frozen

1. Switch the thermostat to emergency heat, which turns the heat pump off and runs backup heat alone.
2. Don’t chip, pry or hammer at the ice; the fins and fan blades bend easily.
3. Don’t pour hot water on it; it refreezes and can damage the coil.
4. Let the ice melt as the weather warms.
5. Switch back to normal heat once the fan turns freely.

The [aux and emergency heat guide](https://blufflinememphisheatpumps.com/guide/auxiliary-emergency-heat/) explains what emergency heat does and why it costs more to run.

## When the power goes out

A heat pump stops when the power goes out. So does a gas furnace: it needs electricity for its blower, igniter, inducer fan and controls.

### Keeping warm without heat

- **Close off rooms** you aren’t using and gather in one space.
- **Close curtains and blinds** at night; open south-facing ones on sunny days.
- **Never use a gas range, grill or unvented heater** indoors for heat; carbon monoxide is a real risk.
- **Protect pipes** on exterior walls and in crawlspaces by opening cabinet doors and, if needed, letting faucets drip.

## When the power comes back

Expect a short delay before the heat pump restarts. Many units wait a few minutes after a power interruption to protect the compressor.

### What else is normal

- **A burst of backup heat** while the heat pump waits and while the cold house recovers.
- **Several defrost cycles** if the coil iced while it was off.
- **A long first run** as the house warms back up.

### What isn’t

- **The outdoor fan not turning** or making a scraping sound, which means ice.
- **Breakers tripped** at the panel or the outdoor disconnect.
- **Strips running for hours** after the house reaches the setpoint.

## Generators

A generator changes what keeps running in the next outage, and the heating type decides how big it needs to be.

| What you want to run | Generator size needed |
| --- | --- |
| Gas furnace blower, igniter and controls | Small; a few kilowatts covers it with other essentials |
| Heat pump alone, no strips | Medium; the compressor’s starting surge is the hard part |
| Heat pump with strip heat | Large; 10 kW of strips alone needs a big generator |
| Strips only (emergency heat) | Large |

### Connecting it safely

A generator feeding the house has to connect through a transfer switch or an interlock installed by a licensed electrician. Backfeeding through an outlet can injure utility workers and damage equipment.

### Dual fuel and outages

A [dual fuel](https://blufflinememphisheatpumps.com/dual-fuel-heat-pump/) system with a gas furnace is the easiest to keep warm on a generator, since the furnace needs only a small one. That is one reason some Memphis owners keep gas even when they add a heat pump.

## All-electric or keep the gas?

Outages are one factor in the choice, not the deciding one. A gas furnace and a heat pump both stop without power, and both restart when it returns. The difference is how much generator each needs.

### How it fits the decision

- **If you plan a whole-house generator**, either works; size it to the heating load.
- **If you’d use a small portable generator**, gas heat is easier to keep running.
- **If you won’t have a generator**, the outage plan is the same either way.

The [gas versus heat pump guide](https://blufflinememphisheatpumps.com/guide/heat-pump-vs-gas-furnace-memphis/) covers running costs, and the [gas furnace to heat pump](https://blufflinememphisheatpumps.com/gas-furnace-to-heat-pump/) page covers the conversion.

## After the storm: what to check

Once the ice is gone and power is back:

- **Look at the outdoor unit** for bent fins, damaged fan blades or limbs on top.
- **Listen** for scraping, grinding or rattling.
- **Watch a defrost cycle** to confirm steam and the fan stopping.
- **Check the condensate drain** on attic units, since a freeze can crack lines.
- **Feel the supply air** in heat mode; it should be warm within a few minutes.

## How long a frozen unit takes to clear

It depends on the weather. Once the air rises above freezing, a coated unit usually clears over several hours to a day. In sun it goes faster.

Running emergency heat in the meantime keeps the house warm without forcing the heat pump to run against ice.

### When to call

If the fan still won’t turn once the surrounding ice has melted, or if the unit runs but blows cool air in heat mode after several defrost cycles, something is damaged or the defrost controls aren’t working. That needs a look before the next cold spell.

## Pipes and drains

Ice storms are hard on the plumbing that runs with a heat pump, too.

- **Condensate lines** from attic air handlers can freeze and crack where they run outside.
- **Exterior hose bibs** near the outdoor unit can split.
- **Crawlspace plumbing** can freeze when the house loses heat for a day.

Check the condensate line on an attic unit once things thaw, since a cracked line can leak into the ceiling the next summer. [Air handler replacement](https://blufflinememphisheatpumps.com/heat-pump-air-handler-replacement/) covers pans, float switches and drain lines.

## Panels and strip heat

Strips are the biggest electrical load in a heat pump system. If you’re planning a generator, smaller strips sized to the house’s real need make it smaller too. The [panel guide](https://blufflinememphisheatpumps.com/guide/electrical-panel-for-heat-pump/) explains strip sizing and circuits.

## The plan in one place

Clear the gutters above the unit, keep the pad draining, switch to emergency heat if the fan freezes, and decide on generator size before you need it. The [defrost guide](https://blufflinememphisheatpumps.com/guide/heat-pump-defrost-ice/) explains normal winter icing, and the [Memphis buying guide](https://blufflinememphisheatpumps.com/guide/memphis-heat-pump-buying-guide/) covers the rest of the decision.

## Questions about this guide

### Can I run my heat pump on a portable generator?

Some can, with a large enough generator and a proper transfer switch or interlock installed by an electrician. The compressor's starting surge is the hard part, and strip heat is a much bigger load than the heat pump itself. Size the generator to what you want to run.

### Should I cover my heat pump before an ice storm?

No. A heat pump runs in winter, and a cover blocks the airflow it needs. If you expect freezing rain, make sure gutters above the unit aren't overflowing and the area around it drains.

### Why does my heat pump take a few minutes to start after the power comes back?

Many units have a built-in delay that protects the compressor after a power interruption. Some thermostats bring on backup heat during that wait. After a few minutes the heat pump restarts on its own.

## Related service

- [Service**Gas furnace to heat pump** Going all-electric means retiring the furnace and capping its gas line. We show you when that pays and when keeping gas is smarter.](https://blufflinememphisheatpumps.com/gas-furnace-to-heat-pump/)

## More guides

- [Learn**Why does a heat pump go through a defrost cycle and ice up in winter?** Frost, steam, a whoosh and a pause are normal. A block of ice that stays isn't. Here is how to tell them apart.](https://blufflinememphisheatpumps.com/guide/heat-pump-defrost-ice/)
- [Learn**What is the difference between auxiliary heat and emergency heat?** Two settings that both turn on the strips, why one is automatic and the other is a last resort, and how to keep the bill in check.](https://blufflinememphisheatpumps.com/guide/auxiliary-emergency-heat/)
- [Learn**Do you need an electrical panel upgrade for a heat pump?** Most heat pump jobs reuse the existing circuits. Here is when they don't, what a load calculation checks, and how smaller strips avoid an upgrade.](https://blufflinememphisheatpumps.com/guide/electrical-panel-for-heat-pump/)
- [Decision Guide**How do you buy the right heat pump for a Memphis house?** The whole decision in the order you meet it, from the system you have now to the readings you should get at start-up.](https://blufflinememphisheatpumps.com/guide/memphis-heat-pump-buying-guide/)

## Get an estimate for your house

(901) 657-2200