Heat Pump Running Constantly
Heat pumps are designed to run longer cycles than traditional furnaces, so some constant running is normal, especially in very cold or hot weather. However, if your home never reaches the set temperature or your energy bills spike unexpectedly, there may be a problem with sizing, refrigerant levels, or the defrost cycle.
- 1Check outdoor temperature - Heat pumps normally run continuously when it's below 30°F or above 95°F outside.
- 2Verify thermostat settings - Make sure it's not set to "emergency heat" or "aux heat" which runs constantly.
- 3Replace the air filter - A dirty filter makes the system work harder and run longer to reach temperature.
- 4Check the outdoor unit - Remove leaves, snow, or ice buildup that could restrict airflow.
- 5Inspect for ice on outdoor coils - Light frost is normal, but thick ice indicates a defrost problem.
- 6Check all vents - Make sure supply and return vents are open and unobstructed.
- Extreme outdoor temperatures
This is often normal. Heat pumps run longer cycles to maintain temperature when it's very cold or hot.
- Undersized equipment
If the heat pump is too small for your home, it will run constantly trying to keep up.
- Low refrigerant
A leak reduces efficiency, causing the system to run longer to achieve the same heating/cooling.
- Defrost cycle problems
If the defrost cycle isn't working, ice builds up and reduces efficiency dramatically.
- Dirty coils or filter
Restricted airflow makes the system work harder and run longer.
- Poor home insulation
Heat loss through poor insulation, drafty windows, or air leaks forces the system to run more.
- Stuck reversing valve
This valve switches between heating and cooling. If stuck, efficiency drops significantly.
- Your home never reaches the set temperature
- Energy bills have increased significantly without explanation
- The outdoor unit is covered in thick ice that doesn't melt
- You hear unusual sounds like grinding, squealing, or loud buzzing
- The system is running but blowing cold air in heating mode (or vice versa)
- The heat pump is less than 5 years old and running constantly - may be sizing issue