If you are new to owning a heat pump, the first really cold week of winter can be stressful. You might notice the unit outside humming away for hours without stopping. To some homeowners, their heat pumps seem to run 24/7.
This leads to many homeowners wondering if a constantly running heat pump is broken and if it’s going to cost them a fortune. Don’t panic. In most cases, a heat pump running constantly in cold weather is actually a sign that it is working efficiently, not that it is failing. However, there are a few exceptions.
Here is why your heat pump runs non-stop, why it’s different from a furnace, and how to tell if you actually have a problem.
The “Cruise Control” Effect: Why Continuous Running is Good
To understand why your heat pump runs so long, you have to stop thinking about it like a gas furnace.
A Gas Furnace is like a sprinter. It blasts 100% of its heat into your home for 10 minutes, overheats the room slightly, and then shuts off completely until the temperature drops.
A Heat Pump is like a marathon runner (or a car on cruise control). Especially if you have a modern variable-speed system. Heat pumps are designed to run at lower, steadier speeds for longer periods.
By running constantly at a lower capacity, your heat pump maintains a perfectly even temperature. Often, this actually uses less electricity than furnaces that frequently start and stop.
Why Heat Loss Forces Constant Running
To understand why your unit won’t turn off, you have to look at how your home loses heat.
- In Mild Weather: Your home loses heat slowly. The heat pump can quickly warm the house up and then take a break.
- In Freezing Weather: Your home “leaks” heat very fast through windows, doors, and insulation.
Eventually, you hit a specific outdoor temperature called the Balance Point. This is the moment where heat is escaping your house at the same speed the heat pump is creating it.
Because the race is tied, the heat pump cannot afford to take a break. If it stops for even ten minutes, your home will immediately get colder. It runs constantly, not because it is struggling, but because it is maintaining that perfect equilibrium.
3 Reasons Your Heat Pump Might Struggle (That Aren’t Breakdowns)
If your unit is running constantly, check these three things before calling for service:
1. You Are Turning the Temperature Way Down at Night
With a gas furnace, we are taught to turn the heat down to 60°F at night to save money. Do not do this with a heat pump in deep winter. If you let the house drop to 60°F, the heat pump has to work incredibly hard to bring it back up to 68°F. It will likely fail to do so efficiently and will trigger your Backup Heat Strips (which are much more expensive to run).
The Fix? “Set it and forget it.” Find a comfortable temperature and leave it alone, or only adjust it by 1–2 degrees.
2. Your Air Filter is Dirty
A clogged filter restricts airflow. If the heat pump can’t breathe, it can’t move heat. It will run endlessly trying to satisfy the thermostat but never quite getting there.
The Fix? Check your filter monthly, especially during heavy use seasons.
3. It’s in Defrost Mode
In freezing weather, you might see steam rising from your outdoor unit or hear a “whooshing” sound. This is likely the Defrost Cycle. The unit temporarily reverses itself to melt ice off the outdoor coils.
The Fix? Wait 10-15 minutes. If it goes back to heating normally, it’s fine.
When to Call a Pro: The Red Flags
While constant operation is usually fine, some signs indicate a real malfunction. Call Allied Air Conditioning & Heating for professional heat pump services if you notice any of the following issues.
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The House is Getting Colder:
If the unit is running non-stop but the indoor temperature is dropping (e.g., it’s set to 70°F but the room is 64°F), your unit may be low on refrigerant, or the compressor may be failing.
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Cold Air from Vents:
While heat pump air feels cooler than furnace air (usually 90-100°F vs 120°F), it should still feel warm-ish. If the air coming out is ice cold, your auxiliary heat strips might be broken.
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The Unit is a Block of Ice:
A light frost is normal. A thick layer of ice encasing the entire unit means the defrost cycle isn’t working.
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Grinding or Screeching Noises:
A steady hum is normal. Metal-on-metal sounds are not.
Need a Winter Check-Up?
If you’re still worried that your heat pump is struggling to keep up with the Illinois winter, don’t guess.
Allied Air Conditioning and Heating has been serving the Northwest Suburbs since 1969. Our NATE-certified technicians can check your refrigerant levels, test your backup heat strips, and ensure your system is running safely.
Contact us today to schedule a service or maintenance visit!
