Signs your air source heat pump needs repairs

Air source heat pumps are one of the smartest ways to heat your home. They’re efficient, low-carbon, and increasingly supported by government incentives. But – like any hard-working system, they’re not immune to wear and tear. 

When problems crop up, you need to act fast. Ignoring early warning signs can lead to higher energy bills, unexpected breakdowns, expensive repairs, and could cause long-term damage or void your warranty.

Is your air source heat pump acting up? Are your energy bills going up? Discover the common warning signs of trouble and learn the next steps to take for fast, effective repairs.

Common signs your heat pump may need repairs

Reduced heating or cooling performance

If your home no longer feels as warm or cool as it used to, your heat pump may be struggling. This could be due to low refrigerant levels, a dirty filter, or a failing compressor, leading to increased, expensive running costs and system strain.

Unusual noises

Buzzing, grinding, rattling, or hissing? These sounds aren’t just irritating, they can indicate serious issues such as refrigerant leaks, loose internal parts, or electrical faults.

Inconsistent temperatures or poor airflow

If some rooms are warm while others remain cold, or the airflow from your vents is weaker than usual, there could be a blocked filter, damaged ductwork, or a problem with the fan or blower motor.

Frequent cycling or irregular operation (turning on and off too often)

Short, repetitive on-off cycles usually point to a problem with the thermostat, sensor calibration, or refrigerant charge. This wastes energy and wears components out faster.

Ice buildup on the outdoor unit

A light layer of frost is normal in colder weather, but if ice doesn’t melt during the defrost cycle or builds up excessively, it could indicate low refrigerant, a faulty defrost system, or restricted airflow.

Leaks or water stains

If water is pooling around the indoor unit, staining walls or floors, or not melting away during the defrost cycle, this could be due to a blocked condensate drain, frozen coil, or refrigerant leak. These issues lead to mould and water damage.

Burning or unusual smells

Strange smells – especially burning or musty odours – shouldn’t be ignored. These could indicate electrical faults, overheating components, or a clogged condensate drain. If you smell burning, switch the system off immediately and call a technician.

Unexplained increase in energy bills

A sudden hike in your electricity bill could be a sign that your heat pump is working harder than it should. When components start to fail, like the compressor or fan motor, your system runs less efficiently.

The system is not turning on or has electrical issues

If your system won’t start or trips your circuit breakers, the issue could be electrical. It might be a faulty capacitor, relay, or a serious compressor fault requiring urgent attention.

Age and frequent repairs

If your heat pump is over 10 years old and you’re regularly calling for repairs more frequently, it may be reaching the end of its working life. Repeated faults are a sign that a replacement or thorough inspection is needed.

An increase in energy bills can be the first sign a service is needed

A sudden increase in your energy bills is often the most noticeable and primary sign that your air source heat pump may require servicing. 

When a system is not functioning efficiently, due to issues such as wear and tear, faulty components, or lack of regular maintenance, it typically consumes more energy to deliver the same level of heating or cooling, which is directly reflected in higher utility costs. 

If you notice your bills rising unexpectedly, even after accounting for seasonal changes or energy price fluctuations, it is important to investigate further, as this could indicate an underlying problem with your equipment that needs professional attention. 

Addressing these issues promptly can help restore efficiency, prevent further damage, and ultimately save you money on future energy bills

What to do when you have problems with your air source heat pump

Not every issue with your air source heat pump needs immediate professional attention. Some of the most common faults are easily fixed, especially if the system hasn’t been cleaned or checked in a while.

Here are some practical steps you can take before calling in a technician:

Check and replace the air filters

Clogged or dirty filters are a leading cause of poor performance, restricting airflow and putting unnecessary strain on key components. Check your filters monthly, especially during winter or summer. If they’re dusty or discoloured, clean or replace them based on the manufacturer’s guidance.

Clear debris from the outdoor unit

Dirt, snow, or garden clutter can block the airflow around your outdoor unit, causing ice buildup or overheating. Both can reduce efficiency and lead to faults. Keep snow or frost from building around the base of the unit. Ensure there are no obstructions around the outdoor unit, allowing at least 30 cm clear space on all sides. 

Check your thermostat settings

If your heat pump isn’t switching on or keeping the correct temperature, it could be a simple settings issue. Incorrect modes or dead batteries are surprisingly common culprits. Check that your thermostat is set to the correct mode, replace batteries if they haven’t been changed in a while, and check that temperature settings haven’t been changed by mistake.

Try resetting the system

Some modern heat pumps will show a fault code when something goes wrong, which can often be cleared by a reset. This might not address deeper issues but could fix minor glitches. Refer to your manufacturer’s manual to safely reset your system. If the fault reappears, seek a professional diagnosis.

Check the power supply

If your system won’t start at all, the issue may be electrical. Check your fuse box to see if a breaker has tripped, and reset if safe to do so. Ensure the unit’s plug is secure and the power switch turned on (often near the indoor air handler). If the lights flicker when the unit reboots, or it keeps tripping breakers, this indicates a deeper electrical issue, and you should contact a professional.

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Important note

If after these checks your heat pump still isn’t working properly, or if you’re still unsure, don’t take it apart or inspect internal components. Heat pumps contain pressurised refrigerant, electrical wiring, and moving parts that require specialist knowledge to diagnose and repair safely.

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When to call in the experts

While the issues above can be resolved with a quick fix, others will need specialist tools, knowledge and certification. If your system is showing signs of deeper faults, don’t delay – you’ll prevent more expensive damage down the line. Get a qualified engineer to advise whether a full repair, part replacement or system upgrade is the best option.

Why it pays to act quickly:

• Minor faults can often be fixed quickly and cost-effectively if discovered early.
• Delaying a service can turn a small issue into an expensive repair or even a system replacement.
• Most warranties require professional servicing and approved repairs – unauthorised work or neglect may void your coverage.
• Reliable heating and cooling mean no cold snaps or sticky nights while you wait for a fix.

Protect your warranty

Most manufacturers require regular servicing and professional repairs to keep warranties valid. If a component fails with no service history or with evidence of a DIY fix, you may be liable for the full cost of repair or replacement. Booking professional repairs keeps you compliant, safe and protected.

Maintain home comfort and keep energy bills under control

A struggling heat pump isn’t just inefficient – it’s unstable. You could be left unprotected during cold snaps and warmer months. Timely repairs ensure your system runs smoothly and efficiently, supporting a greener, low-impact home.

Want to avoid costly surprises?

If you’ve noticed any of these signs, don’t wait to find out how ServiceMy can help you with annual servicing going forward.