Frost Heat Pump Doctor is a plain-English Wellington troubleshooting guide for common heat pump symptoms. It is designed to help you decide whether there is a simple user check worth trying or whether the system needs a qualified technician.
Safety first: do not open electrical covers, handle refrigerant components, bypass safety devices or dismantle the unit. If there is smoke, burning, sparking, significant water near electrical equipment or another immediate safety concern, switch the system off if safe to do so and seek qualified help.
My heat pump is running but not heating
60-second checks
- Confirm the unit is in HEAT mode, not AUTO, COOL or DRY.
- Set the temperature several degrees above the current room temperature.
- Check that filters are reasonably clean and airflow is not blocked.
- Give the system a few minutes. Heat pumps can pause indoor airflow while the coil warms or during defrost operation.
- Look at the outdoor unit. Heavy ice that does not clear, unusual noises or a unit that never runs can indicate a fault.
Call Frost when: the unit repeatedly fails to heat, airflow stays cold, it trips power, displays a recurring fault code, or the outdoor unit behaves abnormally.
My heat pump is leaking water inside
What can cause it?
Common causes can include a blocked or restricted condensate drain, installation fall/drainage issues, a dirty coil or filter contributing to icing, or another fault causing excess condensation.
Do not keep running a unit that is actively leaking onto walls, ceilings, furniture or electrical equipment. Switch it off if necessary and arrange diagnosis.
My outdoor unit is icing up
Some frost can be normal
During cold, damp weather a heat pump can temporarily frost on the outdoor coil and enter a defrost cycle. The indoor fan may pause while the system clears the ice.
Not normal: thick ice that remains for long periods, repeated severe icing, poor heating that never recovers, or unusual noises. Those symptoms deserve a technician rather than a kettle of hot water or DIY dismantling.
My heat pump smells
| Smell | Possible next step |
|---|---|
| Dusty after not being used | Check/clean accessible filters and monitor. |
| Musty | Filters, coil or drainage may need cleaning/service. |
| Burning/electrical | Turn the system off if safe and arrange qualified inspection. |
| Persistent unusual chemical smell | Stop using the system and arrange diagnosis. |
My heat pump is making a strange noise
Clicking, ticking or expansion sounds
Some operating noises can be normal as materials warm, cool and change pressure.
Rattling or vibration
Could be a loose panel, mounting issue, debris, fan problem or another mechanical issue.
Grinding, screeching or severe mechanical noise
Stop the system if safe and arrange a technician. Continuing to run a system with a serious mechanical noise can worsen damage.
My heat pump has an error code
Do not assume an internet code list is definitive. Error codes differ by brand, model and controller. Write down the exact code, brand and model number, and note what the system was doing when the fault appeared.
Frost works across major heat pump brands including Fujitsu, Daikin, Mitsubishi Electric, Panasonic, Hitachi and Gree. A technician can use the exact system information and fault history to diagnose the cause.
My heat pump keeps turning on and off
Short cycling can be related to temperature settings, airflow restrictions, sensor behaviour, sizing, system control or a fault. If the behaviour is new or excessive, it is worth diagnosing rather than assuming the unit simply needs replacement.
My heat pump won’t turn on at all
- Check the remote batteries and display.
- Check whether the property has power and whether other appliances are affected.
- If you know which normal household circuit supplies the heat pump, check whether the breaker has tripped. Do not repeatedly reset a breaker that trips again.
- Note any lights or error indicators on the indoor unit.
If a breaker repeatedly trips, there is a burning smell, or the unit remains dead, arrange qualified service.
My heat pump is not cooling properly
- Confirm COOL mode and an appropriate set temperature.
- Check accessible filters and airflow.
- Close unnecessary doors/windows while testing.
- Check whether strong afternoon sun or an unusually large heat load has changed the room conditions.
Persistent poor cooling can be caused by airflow, controls, sizing, coil condition, refrigeration faults or other issues that require proper diagnosis.
Repair or replace?
Replacement is not automatically the right answer. Frost considers the fault, age and condition of the equipment, likely repair cost, parts availability, efficiency, refrigerant/system type and whether the existing unit is appropriately sized for the space.
| Situation | Often worth considering |
|---|---|
| Minor serviceable fault on otherwise sound equipment | Repair |
| Dirty system / airflow issue | Service and reassess |
| Repeated major faults on older equipment | Compare repair with replacement |
| Poor performance since installation | Check sizing, placement and installation before blaming age |
| Parts unavailable / major component failure | Replacement may become more practical |
What to send Frost before a repair visit
- Brand and model number if accessible.
- Exact error code or flashing-light pattern.
- A short video of any unusual noise.
- A photo showing the indoor unit and any leak/ice.
- When the problem started and whether it is intermittent.
This information can make fault finding faster and helps us arrive with better context.
Wellington Region heat pump repairs
Frost Industries provides heat pump diagnostics, repairs and servicing across the wider Wellington Region including Wellington City, Porirua, Lower Hutt, Upper Hutt and Kāpiti Coast, with wider project coverage by arrangement.
Need an actual diagnosis? Call 0800 346 358 or request a Frost assessment.
Important
This guide is general troubleshooting information, not a remote diagnosis. Heat pumps contain mains-voltage electrical components and pressurised refrigerant systems. Work requiring electrical, refrigeration or regulated trade skills should be carried out by appropriately qualified people.