A clicking sound when your heat pump fires up is one of the most common concerns NZ homeowners raise — and the good news is it's often completely normal. However, persistent, loud, or irregular clicking can point to something that needs attention. Here's how to work out what's going on and what you can safely do about it.
Is the Clicking Normal?
Most heat pumps produce a brief click or two on startup and shutdown — this is simply the contactor relay switching the compressor on, or the plastic casing expanding and contracting with temperature changes. If the clicking stops within a few seconds and the unit runs quietly, you can generally relax.
You should investigate further if:
- The clicking is loud, repetitive, or rhythmic during operation
- The unit clicks but fails to start (no airflow, no heating or cooling)
- You hear clicking accompanied by grinding, rattling, or buzzing
- The clicking has changed recently or become more frequent
Common Causes of Clicking on Startup
1. Thermal Expansion of the Casing
As the unit warms up, plastic panels expand and can tick or click against the frame. This is harmless and usually settles within a minute or two. No action needed.
2. Loose Fan Blades or Debris in the Outdoor Unit
Leaves, twigs, or small stones can get caught in the outdoor unit's fan, causing a repetitive clicking as the blade strikes the object. Turn the unit off at the wall before inspecting. Carefully remove any visible debris through the grille — do not reach inside or remove the casing.
3. Dirty or Blocked Filters
A clogged filter forces the unit to work harder, which can cause unusual noises including clicking from the indoor fan motor straining. Check and clean your filters — most manufacturers recommend doing this every 4–6 weeks during heavy use. Refer to your owner's manual for the correct procedure; it's a simple DIY task on most models.
4. Loose Panels or Screws
Vibration over time can loosen the outer casing panels. With the unit switched off and isolated, gently press on panels to find any that rattle. Tighten any accessible screws with a suitable screwdriver. If panels are cracked or broken, contact your installer or a heat pump technician.
5. Faulty Contactor or Relay
The contactor is an electrical switch that engages the compressor. A worn or failing contactor can produce rapid, repeated clicking as it struggles to make a solid connection. This is an electrical fault and must be diagnosed and repaired by a licensed professional — see below.
6. Compressor Issues
If the clicking is coming from the outdoor unit and the system isn't cooling or heating properly, the compressor itself may be struggling to start — sometimes called "hard starting." This is a serious fault requiring a qualified heat pump technician.
7. Refrigerant Flow Sounds
Some clicking or gurgling on startup is simply refrigerant moving through the system as pressures equalise. This is normal and typically brief.
What You Can Safely Check Yourself
As a homeowner, you can safely:
- Clean or replace the indoor air filters (follow your manual)
- Clear debris from around and inside the outdoor unit grille (unit off at the wall)
- Check that the outdoor unit is level — an unlevel unit can cause vibration and noise
- Ensure nothing is leaning against or touching the outdoor unit
- Tighten visible, accessible screws on the outer casing (unit off)
- Check the remote or wall controller for error codes and look these up in your manual
Always switch the unit off at the wall isolator before doing any physical checks near the outdoor unit.
What You Must NOT Do Yourself
Heat pumps involve high-voltage electricity and pressurised refrigerant. Under NZ law, the following are restricted electrical work and must only be carried out by a registered electrician or licensed heat pump technician:
- Opening the electrical enclosure or touching wiring
- Replacing contactors, capacitors, or control boards
- Handling or topping up refrigerant (also requires an EPA refrigerant handling licence)
- Any internal repair to the compressor or fan motor
For more on what constitutes restricted electrical work in New Zealand, see the Electrical Workers Registration Board (EWRB).
WorkSafe NZ also has guidance on electrical safety around appliances.
When to Call a Professional
Call a licensed heat pump installer or technician if:
- The clicking is persistent or getting worse
- The unit won't start or is not heating/cooling effectively
- You suspect a contactor, capacitor, or compressor fault
- You see error codes you can't resolve with the manual
- The unit is tripping your switchboard or blowing fuses
- Your heat pump is out of warranty and due for a service anyway
Regular servicing (typically every 1–2 years by a professional, plus your own filter cleaning) keeps your heat pump running efficiently and can catch small issues before they become expensive repairs. You can find qualified local heat pump installers and technicians on tradedirectory.co.nz.
For guidance on energy-efficient heat pump use and maintenance, Energywise has helpful NZ-specific advice. If you're a landlord, note that heat pumps may be relevant to your obligations under the Healthy Homes standards.
ISO 9001
