Troubleshooting Your Heat Pump: Don't Let Winter Catch You Cold

Winter in New Zealand brings stunning landscapes for a lucky few and thanks to heat pumps, warm, cozy nights. These efficient systems keep our living spaces warm and dry, making those frosty mornings a lot more bearable. What happens, though, when your trusty heat pump suddenly decides to act up? Perhaps it is blowing cold air, making strange noises, or not turning on at all.

Dealing with a heat pump not working can be frustrating, especially when the temperatures drop. You are not alone! Many New Zealand homeowners encounter common heat pump problems that, with a little knowledge, can often be resolved or at least understood before calling in the professionals.

Serving homeowners across New Zealand for years, OneAir has provided heat pump repair services all year round, and we’ve gathered the most common heat pump problems and their quick fix to troubleshoot the issue. This comprehensive guide is designed to be your go-to resource for troubleshooting common heat pump issues. We will walk you through the symptoms, potential causes, and what you can do. Our goal is to empower you to keep your home warm and your family comfortable throughout the winter season, whether that means a simple DIY fix, scheduling a much-needed heat pump repair, or considering a brand new, efficient heat pump installation.

Let us dive in and get your heat pump back to peak performance!

How to Troubleshoot Common Heat Pump Problems

Heat Pump Problem # 1: The Silent Treatment - Your Heat Pump Isn’t Turning On

There is nothing quite as unsettling as a silent heat pump when you are expecting warmth. If your heat pump is completely unresponsive, here are the first things to check:

Defrost mode: One of the few weaknesses of heat pumps is that when the outside temperature drops to around 7 degrees and humidity is high, the coils can ice up, rendering the heat pump temporarily disabled. The system will enter a warm up cycle to defrost the ice before it starts working again. The good news is that all this is fully automated and you do not need to do anything but wait for the system to turn itself on again - usually within 15-30 min or so. 

• Power Supply Issues: This might sound obvious, but based on our callout experience, it is far and away the most common culprit.

  • Check the Breaker: Go to your home's electrical board and look for a tripped breaker labeled for your heat pump. If it is still in the “on” position, flip it firmly to the "off" position and then back to "on." If it trips again immediately, do not try to reset it repeatedly. This indicates a more serious electrical issue and requires an electrician.

  • Outdoor Isolator Switch: Most outdoor heat pump units should have a dedicated isolator switch on or near the unit itself. Ensure it is in the "on" position. Sometimes, it gets accidentally switched off.

  • Remote Control Batteries: While it may seem minor, dead batteries in your remote control can make it seem like the unit itself is not responding. Replace them and try again.

• Handheld or Wall mounted remote control Settings: Your thermostat is the brain of your heat pump system.

  • Correct Mode: Ensure your thermostat is set to "Heat" mode, not "Cool" or "Fan Only."

  • Temperature Setting: Double-check that your desired temperature setting is higher than the current room temperature. If it is set lower, the unit will not turn on to heat.

  • Programming Errors: If you have a timer on your remote control, review its schedule settings to ensure it is set to operate during the times you need heating. Accidental programming can lead to unexpected shutdowns.

• Safety shutdown: Modern heat pumps have built-in safety features. If there is a serious problem, the unit may enter a lockout or restricted operation mode to prevent further damage. This often requires a power cycle (turning the unit off at the isolator for a few minutes and then back on) to reset, but if the underlying issue persists, it will lock out again.

If, after these checks, your heat pump remains stubbornly silent, it is time to consider professional heat pump repair.

Heat Pump Problem # 2: The Cold Shoulder - Your Heat Pump is Blowing Cold Air

This is perhaps the most frustrating heat pump problem for New Zealand homeowners. You expect warm air, but all you get is an icy breeze. Here are the common reasons and what you can do:

• Incorrect Mode Setting: This is often overlooked. Just like with a unit that will not turn on, ensure your remote or wall controller is set to "Heat" mode. If it is accidentally set to “Automatic” or "Cool," it could indeed blow cold air.

• Thermostat Issues:

  • Low Temperature Setting: If your set point temperature is set too low (below the current room temperature), the heat pump will not engage the heating cycle. And if it is in ‘Automatic’ mode, the system may even switch  to cooling mode and blow cold air until it reaches the requested temperature.

  • Fan Only or Dehumidify Modes: Make sure your thermostat is not in “Dehumidify” or "Fan" modes. Dehumidify will usually blow cold air while fan only mode will circulate air, but not heat it.

• Dirty Air Filters: A surprisingly common cause! Clogged air filters restrict airflow significantly. This forces your heat pump to work harder, can lead to coil freezing up (which then blows cold air as the system tries to thaw - see “defrost mode”), and reduces heating efficiency.

  • The Fix: Locate your indoor unit's air filters (usually behind the front panel). Pull them out and inspect them. If they are visibly dirty with dust and debris, clean them according to your manufacturer's instructions (often rinsing with water and allowing them to dry completely) or replace them if they are broken. This simple step can dramatically improve performance and prevent many heat pump problems.

• Refrigerant Issues (Low or Leaking): Refrigerant is the fluid that absorbs and releases heat in your system.

  • Symptoms: If your heat pump is low on refrigerant due to a leak, you will likely notice insufficient heating, ice build up on the outdoor unit (even when not in defrost mode), or a hissing sound.

  • The Fix: This is not a DIY job. Handling refrigerant requires specialised tools, training and “Approved Gas Handler” qualification. If you suspect a refrigerant issue, you absolutely need a certified technician for this type of heat pump repair.

• Defrost Cycle: Heat pumps periodically enter a defrost cycle, especially in colder temperatures, to melt any ice that has formed on the outdoor coil. During this cycle, the indoor unit will stop blowing warm air (and may even blow cool air briefly) and the outdoor unit fan may stop while a "steam" or fog appears. This is normal operation.

  • How to Tell: Most modern heat pumps have an indicator light that illuminates when in defrost mode. The cycle typically lasts only a few minutes. If it is happening constantly or for very long periods, it could indicate a problem, usually an undersized system .

• Outdoor Unit Blockages: The outdoor unit needs unrestricted airflow to function correctly.

  • Check For: Ensure there are no shrub, , leaves, or other debris blocking the coils or fan. Clear any obstructions carefully. Maintain at least 60cm of clear space around the outdoor unit.

If you have checked these points and your heat pump is still blowing cold air, it is time to call for professional heat pump repair.

Heat Pump Problem # 3: The Racket - Strange Noises Coming From Your Heat Pump

Heat pumps typically operate quietly, but sometimes they can develop an unusual sound. These noises often indicate a specific problem:

• Screeching or Squealing: This often points to a worn fan motor bearing, either in the indoor or outdoor unit. It is a sign that the fan motor is under strain and needs attention before it burns out completely.

• Clicking: A repetitive clicking sound, especially when the unit tries to start, could indicate a faulty relay or capacitor. These components are essential for the motor to start correctly and also require immediate repair.

• Banging or Clanking: Loose fan blades hitting the casing, debris inside the outdoor unit, or a failing compressor can cause these louder, more concerning noises. If you hear banging, turn the unit off immediately to prevent further damage and call an approved heat pump repair agent.

• Hissing or Gurgling: A hissing sound often suggests a refrigerant leak. Gurgling can also be associated with refrigerant issues or trapped air in the system. As mentioned, this is a specialised area that need a suitably-qualified HVAC technician to undertake the repair

• Buzzing: Electrical issues like a failing transformer, loose wiring, or a contactor problem can cause a buzzing sound. Immediately turn off the system using the isolator and breaker switch at the electrical distribution board  and call a qualified heat pump technician to undertake the repair.

While some of the above can be done by homeowners themselves (e.g. clearing external debris), most strange noises require a skilled and qualified technician with specialised tools for diagnosis and heat pump repair. Ignoring unusual sounds can lead to more significant and more expensive problems down the line.

Heat Pump Problem # 4: The Drip - Water Leaking From Your Indoor Unit

Seeing water leaking from your indoor heat pump unit is alarming and can cause damage to your home. Here is why it might be happening:

• Clogged Condensate Drain Line: Water is a normal  byproduct of correct  heat pump operation as it removes moisture from the air. Your system is designed to collect this water in a drain pan and direct it outside through a condensate drain line. Over time, the accumulation of dust mixed with water can see algae, mould, or debris block forming that can clog this line, causing the drain pan to overflow and leak down the wall.

  • The Fix (Careful DIY): You can try to clear a minor clog. Locate the drain line (it is usually a PVC pipe leaving the indoor unit). You can try to gently flush it with a mixture of distilled vinegar and water or appropriate plumbing cleaner. If the clog is stubborn or if you are uncomfortable doing this work and worry you could cause other damage by doing so, call a professional.

• Cracked or Damaged Drain Pan: Less common, but possible, is a crack in the drain pan itself, allowing water to escape.

• Frozen Evaporator Coil: If the indoor coil freezes due to restricted airflow (dirty filter!) or low refrigerant, the ice will eventually melt and overwhelm the drain pan, causing a leak inside.

• Improper Installation: If the unit was not installed with the proper slope for drainage, water can back up and eventually leak.

Water leaks can lead to mould growth and even structural damage, so addressing them promptly is crucial to your family’s - and your home’s - health.

Heat Pump Problem #5: The Ice Age - Ice Build Up on Your Outdoor Unit

While some frost on the outdoor unit during colder weather is normal and will be handled by the defrost cycle, excessive ice or ice that persists indicates a problem.

• Malfunctioning Defrost Cycle: The most common cause. The defrost sensor or board might be faulty, preventing the unit from initiating or completing its defrost cycles.

• Low Refrigerant: Low refrigerant causes the coils to run at abnormally low temperatures, leading to ice formation.

• Dirty Outdoor Coil: A coil covered in dirt or debris cannot exchange heat effectively, leading to lower coil temperatures and potential ice formation.

• Fan Motor Issues: If the outdoor fan is not working correctly, airflow over the coil will be reduced, leading to ice build up.

Do not try to chip away ice with sharp objects, as you can damage the delicate coils. If you see persistent or excessive ice, it is a clear sign that professional heat pump repair is needed.

Heat Pump Problem # 6: Diminished Performance - Your Heat Pump Isn’t Heating as Well as Before

Perhaps your heat pump is working, but your home just does not feel as warm as it used to, or it takes much longer to reach the desired temperature. This decline in performance can be attributed to several factors:

• Dirty Air Filters (Again!): We cannot stress this enough. A clogged filter severely reduces airflow and heat transfer, making your unit less efficient.

• Blocked Outdoor Coil: Just like a dirty indoor filter, a dirty outdoor coil prevents proper heat exchange. Clear away any leaves, dirt, or debris.

• Leaky Ductwork (Central /Ducted) heat pump: If your heat pump is connected to a duct system, leaks in the ducts can lose a significant amount of heated air before it reaches your rooms. This is especially common in older homes.

• Refrigerant Issues: Low refrigerant reduces the system's ability to transfer heat.

• Aging System: Like any appliance, heat pumps become less efficient as they age. Components wear out, and the system may simply struggle to meet your heating demands, especially in colder temperatures.

• Undersized Unit: If your heat pump was improperly sized for your home when installed, or if you have made renovations and extensions that have increased your home's heating load, it may struggle to reach and maintain the correct temperature..

Addressing these issues, from simple cleaning to professional heat pump repair or even considering a new installation, can restore your home's comfort.

How to Prevent Heat Pump Problems: The Power of Maintenance

Many heat pump problems can be avoided or significantly reduced with regular maintenance. Just like your car, your heat pump needs a tune up to run efficiently and reliably.

• Regular Filter Cleaning/Replacement: Make it a habit. Check your filters monthly during the heating season and clean them as needed. This is the single most effective thing you can do as a homeowner.

• Keep Outdoor Unit Clear: Periodically check and clear away any leaves, shrubs, grass ,, or other debris from around your outdoor unit. Ensure nothing is blocking the airflow.

• Professional Annual Servicing: This is arguably the most important preventative measure. A qualified HVAC technician will:

  • Clean coils and components.

  • Check refrigerant levels and pressure.

  • Inspect electrical connections.

  • Lubricate moving parts.

  • Test thermostat calibration.

  • Identify potential issues before they become major heat pump problems.

Investing in annual heat pump servicing not only helps prevent breakdowns but also ensures your unit operates at peak efficiency, saving you money on your power bills.

When to Call the Professionals for Heat Pump Repair or Replacement

While some troubleshooting steps can be done by a homeowner, many heat pump problems require the expertise of a qualified and experienced HVAC technician. Do not hesitate to call if:

• You suspect a refrigerant leak.

• The unit is making loud, unusual, or grinding noises.

• There is a persistent electrical issue (tripping breakers).

• Your unit is leaking a significant amount of water.

• You have performed basic checks, but the problem persists.

• You notice excessive ice build up on the outdoor unit.

• Your heat pump is old and frequently breaking down.

• You are considering a new heat pump system and need advice on the right size and type for your home.

If your heat pump is less than 5 years old (6 or 7 in the case of some brands), call the installer or an approved repair agent immediately as  most repairs will be undertaken free of charge under warranty. Even if your heat pump is over 5 years old,  trying to fix complex heat pump problems yourself can be dangerous and lead to further damage, increasing your repair bill even more. Professional technicians have the tools, training, and knowledge to diagnose issues accurately and perform safe and effective heat pump repairs.

Planning for Winter Comfort: New Heat Pump Installations

Sometimes, despite a repair technician’s  best efforts, a heat pump has multiple part failures which indicates it has reached the end of its useful lifespan. If your unit is ten years old or more o, frequently breaks down, or is simply not keeping your home warm and dry, it might be more cost effective in the long run to consider a new heat pump system installation. Modern heat pumps are significantly more energy efficient, use less harmful refrigerant gas, are quieter, and offer advanced features that can typically improve your home comfort and reduce your power bills. As winter approaches, there is no better time to evaluate your heating needs.

• Energy Efficiency: New heat pumps boast impressive energy ratings, meaning more heat output for lower power consumption. 

• Improved Comfort: Consistent temperatures, better dehumidification, and quieter operation (especially important for units installed in bedrooms).

• Smart Features: Many new units offer smart controls, allowing you to manage your home's climate from your phone. Some also have occupant sensors, meaning they use less electricity by slowing down or turning off when it detects people leaving the room 

• Peace of Mind: A new system comes with a 5+ years warranty, providing years of reliable heating and free repairs if it breaks down before that.

Our team specialises in assessing your home's unique requirements and recommending the ideal heat pump system that will provide reliable, efficient warmth for years to come. We handle everything from expert advice and sizing to professional installation, ensuring your home is prepared for whatever New Zealand winter throws at it.

Your Partner in New Zealand Home Comfort

At OneAir, we understand the importance of a warm, dry home, especially during the New Zealand winter. We are committed to providing reliable heat pump repair services, expert advice on new heat pump installations, and preventative maintenance to keep your system running smoothly.

Do not let heat pump problems leave you in the cold. Whether you need a quick fix, a major heat pump diagnosis and repair, or are ready to explore a new, highly efficient heat pump system for your home, our experienced and certified technicians are here to help.

Contact OneAir today at (0800) 663 247 to schedule a service, get a quote for a new installation, or simply to get expert advice on ensuring your home is winter ready. Let us help you ensure your family's comfort this winter and for many seasons to come.