Is your heat pump turning off unexpectedly—sometimes after just a few minutes of running? It’s a frustrating issue, especially when you’re relying on it to keep your home warm during Christchurch’s colder months (or to keep it cool during a hot Canterbury summer).

The good news is: this is a common problem, and in many cases, it’s easy to fix. In this guide, we’ll walk you through the most likely reasons your heat pump keeps shutting off—and what to do about it.

Is It Normal for a Heat Pump to Turn On and Off?

Heat pumps are designed to cycle on and off as needed to maintain the temperature you set. This cycling is a normal part of how the system works.

But if your unit is turning off too frequently—especially before it reaches the set temperature or within just a few minutes—this could be a sign of short cycling, which can reduce efficiency, increase wear and tear, and leave your home uncomfortable.

Top Reasons Your Heat Pump Keeps Turning Off (and How to Fix Them)

1. Incorrect Thermostat Settings

Sometimes, the problem isn’t the heat pump—it’s the thermostat.

• If the set temperature is very close to the current room temperature, the unit may cycle off quickly.
• If your thermostat is set to “Auto” mode in mild weather, it may switch between heating and cooling, causing inconsistent operation.
• A thermostat installed in a drafty or sunny spot may misread the room’s actual temperature and shut the unit off early.

What to try:

Double-check your thermostat settings, and try switching to “Heat” or “Cool” mode rather than “Auto.” Set a temperature a few degrees higher (in winter) or lower (in summer) than the current room temperature.

2. Dirty or Blocked Air Filters

Clogged filters restrict airflow and can cause the system to overheat. Many heat pumps are designed to shut down automatically to protect themselves from damage in this case.

What to try:

Remove and inspect your filters. If they look dusty or clogged, clean them thoroughly or replace them. Regular filter cleaning is one of the easiest ways to keep your system running smoothly.

Read more: How to clean your heat pump

3. Oversized or Undersized Heat Pump

If your system is too powerful for the space, it can heat or cool your room too quickly, then shut off—only to turn back on again a few minutes later. This short cycling can increase energy use and reduce comfort.

An undersized unit, on the other hand, may overheat or overwork, causing premature shutdowns.

What to do:

System size should always be matched to your space by a qualified professional. If you suspect your unit is improperly sized, contact Enviro Master for an in-home assessment.

Read more: What size heat pump do I need?

4. Refrigerant Issues

If your heat pump is low on refrigerant or has a leak, it may not be able to operate efficiently and could shut down to prevent compressor damage.

Signs of refrigerant problems:

• Ice buildup on indoor or outdoor coils
• Hissing or bubbling sounds
• Reduced heating or cooling performance

What to do:

This is not a DIY fix. Call a licensed technician to check refrigerant levels and inspect for leaks.