Don't cover your heat pump during an ice storm — it needs to run
Your heat pump must stay uncovered and able to pull air during an ice storm, even though ice buildup looks alarming. The unit is designed to shed ice on its own through a defrost cycle that reverses the refrigerant flow to warm the outdoor coil. Covering it traps heat and moisture, which can damage the compressor and prevent the defrost cycle from working. The only exception is if your heat pump has stopped running entirely and you cannot reach a technician — in that case, a temporary cover protects it from further ice accumulation while you wait for service.
Ice on the outdoor unit during freezing rain is normal and does not mean the system is failing. Your heat pump is designed to operate in these conditions and will clear the ice automatically every 30 to 90 minutes. Leaving it uncovered and running is always the safer choice.
Key Takeaways
- Heat pumps shed ice automatically through a defrost cycle and need open airflow to do so; covering them prevents this process and risks compressor damage.
- Ice buildup on the outdoor unit is normal during freezing rain and does not mean the system is failing or losing efficiency.
- If your heat pump stops heating during an ice storm, the problem is usually a stuck defrost cycle or low refrigerant, not ice blockage, and requires a technician.
- You can clear ice from the fan shroud and base with your hands or a plastic scraper, but never force ice off the coils themselves.
- A temporary cover is only appropriate if the unit has already failed and you are waiting for emergency service.
How the defrost cycle clears ice automatically
When outdoor temperatures drop below about 40°F and humidity is high, ice forms on the heat pump's outdoor coil. This is normal. Your heat pump detects the ice buildup through a temperature sensor and triggers the defrost cycle — usually every 30 to 90 minutes, depending on conditions.
During defrost, the system reverses the refrigerant flow so the outdoor coil becomes hot instead of cold. This melts the ice off the coil in 5 to 15 minutes. The water drains through the condensate pan at the base of the unit. While defrost is running, your indoor heating switches to electric resistance (your backup heat) so you stay warm. This is why your heating bill rises during ice storms — you are using two heat sources at once.
Covering the unit blocks the airflow the defrost cycle needs to work. It also traps the heat and moisture from defrost inside the cover, which can corrode the coil and damage the compressor over time. The cover defeats the system's built-in protection and creates the very problems you are trying to prevent.
Why ice buildup does not mean your heat pump is failing
Ice on the outdoor unit looks like a breakdown, but it is a sign the system is working. The coil is cold enough to pull heat from the air, which is exactly what you want. The ice forms because the coil is colder than the dew point of the outdoor air.
A heat pump in an ice storm will cycle between heating and defrost mode repeatedly. You may hear the fan stop, see steam or water dripping from the unit, or notice the indoor fan pause for a few minutes while defrost runs. All of this is normal. The system is managing ice the way it was designed to. Your heating may feel less powerful during defrost cycles because your backup electric heat is running instead of the heat pump, but this is temporary and expected.
If your heat pump stops heating altogether and does not restart after 20 to 30 minutes, that signals a real problem — usually a stuck defrost sensor, a failed reversing valve, or low refrigerant. Ice blockage alone does not cause this. Call a technician if heating does not resume.
What you can safely clear by hand
You can remove ice from the plastic fan shroud (the outer casing) and the base of the unit using your hands or a plastic scraper. This helps water drain and improves airflow slightly. Never use a metal tool or force ice off the aluminum coil fins themselves — the coil is delicate and puncturing it means refrigerant loss and a costly repair.
If ice has completely blocked the intake or discharge vents, you can gently break away ice from the shroud edges. Work slowly and stop if you feel resistance. Do not chip at the coil or the tubing. If the ice is thick and stuck, leave it for the defrost cycle to handle. Clear the condensate drain at the base if it is frozen shut — this is a small pipe or tube where water exits. Pouring warm (not boiling) water on the drain opening can thaw it and restore drainage.
When a temporary cover is appropriate
A temporary cover makes sense only if your heat pump has already stopped working and you are waiting for emergency service — usually in a situation where the unit will not run at all and you cannot reach a technician for several hours or days. In this case, a cover prevents additional ice from accumulating while the system is already down.
Use a lightweight tarp or blanket, not a sealed plastic cover. find it loosely so air can still circulate underneath. Remove it as soon as the unit restarts or the technician arrives. Do not leave a cover on for more than a few hours at a time. If your heat pump is still running and cycling into defrost, do not cover it — the risk of damage outweighs any benefit.
How to protect your heat pump before ice storms arrive
Clear leaves, debris, and snow from around the outdoor unit before winter. Ice storms often follow heavy snow, and a unit already buried is more likely to have drainage problems. Keep the area around the unit clear of vegetation and objects that block airflow.
Have your heat pump serviced before the heating season starts. A technician will check the refrigerant charge, test the defrost sensor, and clean the coil. Low refrigerant or a faulty sensor makes ice buildup worse and forces the system to work harder. If your heat pump is more than 10 years old and ice storms are common in your area, ask your technician about a crankcase heater or auxiliary heat strips. These reduce the strain on the system during extreme cold and ice.
What happens to your heating during a long ice storm
During an ice storm lasting 12 hours or more, your heat pump will cycle continuously between heating and defrost. Your heating bill will be noticeably higher because the electric resistance heat runs during each defrost cycle. This is normal and unavoidable — it is the cost of maintaining comfort when the outdoor coil is icing up.
Your indoor temperature may drop slightly (1 to 3 degrees) during defrost cycles, especially if the outdoor temperature is very low. This is temporary and usually unnoticeable. If the temperature drops more than that or does not recover after defrost ends, the system may have a problem and needs service. If the ice storm knocks out power, your heat pump will not run, and neither will your backup heat. Have flashlights, blankets, and a plan to stay warm without electricity.
Frequently Asked Questions
Can ice on the heat pump coil freeze the refrigerant line?
No. The refrigerant inside the tubing is much colder than the ice forming on the outside of the coil, so ice cannot freeze the line itself. The tubing is also insulated. Ice on the outside of the coil is a surface problem, not a sign that the refrigerant is stuck.
Should I pour hot water on the heat pump to melt ice faster?
No. Hot water can damage the coil fins and the electrical components, and it interferes with the defrost cycle. Let the system's own defrost cycle do the work. If you want to help, use warm (not hot) water only on the condensate drain if it is frozen shut.
What if my heat pump is making loud noises during an ice storm?
Some noise during defrost is normal — you may hear the reversing valve click, the fan stop and start, or water dripping. If the noise is a grinding, squealing, or banging sound that does not stop after defrost ends, the system may have a mechanical problem and needs service.
Will my heat pump work at all if it is completely covered in ice?
It will keep trying to run and defrost, but the defrost cycle will be less effective because the cover blocks airflow. The system will overheat, the compressor will work harder, and you risk damage. This is why covering an operating heat pump is harmful.
How long does an ice storm have to last before I should worry about my heat pump?
The system is built to handle continuous ice for 24 hours or more. If your heat pump is running and cycling into defrost regularly, it is doing its job. Worry only if it stops heating entirely or if you hear unusual noises that do not stop after defrost ends.