Seeing an error code flash up on your heat pump's display can be alarming, but it doesn't always mean an expensive repair. Many codes are triggered by simple issues you can sort yourself in minutes — others point to faults that need a licensed professional. Here's how to work through it sensibly.
Step 1: Note Down the Exact Error Code
Before you do anything else, write down the exact code shown on the display or remote controller. Error codes vary significantly between brands (Mitsubishi Electric, Daikin, Fujitsu, Panasonic, Hitachi, and others all use different numbering systems), so the code itself is only meaningful alongside your specific model. Grab your owner's manual — the error code table is usually near the back. If you've lost the manual, most manufacturers publish them on their NZ websites or you can search by model number.
Step 2: Try a Basic Reset First
A surprising number of error codes are caused by a temporary glitch — a power fluctuation, a brief sensor hiccup, or the unit overheating momentarily. Before assuming the worst:
- Turn the heat pump off at the remote or wall controller.
- Switch it off at the isolator switch (the dedicated switch near the indoor unit) or at the switchboard.
- Wait at least 3–5 minutes to allow capacitors to fully discharge.
- Switch it back on and see if the code clears.
If the code disappears and the unit runs normally, keep an eye on it over the next few days. If it returns, there's an underlying issue to investigate.
Step 3: Check the Common Culprits You Can Fix Yourself
Several error codes relate to basic maintenance issues that homeowners can safely address:
Dirty or Blocked Filters
Filter-related codes are among the most common. A clogged filter restricts airflow, causing the unit to overheat or freeze up. Remove the indoor unit's front panel, slide out the filters, and wash them gently under warm water. Allow them to dry completely before reinserting. Filters should ideally be cleaned every 4–6 weeks during heavy use — more often in dusty environments.
Blocked Outdoor Unit
Check that the outdoor unit has clear airflow on all sides. Remove any leaves, debris, or objects within at least 30 cm of the unit. Never operate the heat pump with the outdoor unit covered or boxed in.
Frozen Indoor or Outdoor Coil
In cold weather, the outdoor unit can ice up. Most modern heat pumps run an automatic defrost cycle — if you see ice and the unit has stopped, give it 30–60 minutes to defrost before restarting. If icing is persistent, there may be a refrigerant or airflow issue requiring a technician.
Remote Control or Communication Errors
Some codes simply indicate a communication fault between the remote and the indoor unit. Replace the remote's batteries and re-pair it according to your manual.
Common Error Code Categories (General Guide)
While exact codes differ by brand, most fall into these broad categories:
| Code Type | Typical Cause | DIY Fix? |
|---|---|---|
| Filter/airflow fault | Dirty filter, blocked vents | Yes |
| Temperature sensor fault | Faulty sensor reading | Sometimes (reset first) |
| Communication error | Wiring or controller issue | Reset only; tech if recurring |
| Refrigerant fault | Low gas, leak | No — licensed tech required |
| Compressor fault | Mechanical failure | No — licensed tech required |
| Drainage fault | Blocked condensate drain | Often yes — clear the drain |
Clearing a Blocked Condensate Drain
If your unit is displaying a drainage error or you notice water dripping inside, the condensate drain line may be blocked. This is usually a small plastic pipe running from the indoor unit to outside or to a drain. You can often clear a minor blockage by flushing it with warm water or using a wet/dry vacuum at the outlet end. If you're unsure where the drain exits, or if the blockage persists, call a technician.
What You Cannot and Should Not Touch
Some faults are beyond DIY — and attempting them yourself can be dangerous or illegal in New Zealand:
- Refrigerant (gas) handling is restricted under NZ law. Only a certified refrigeration technician (holding an appropriate EWRB or industry certification) may handle refrigerants. Never attempt to top up or check gas pressure yourself.
- Electrical wiring inside the unit or at the isolator is restricted electrical work under the Electricity Act. Only a registered electrician may carry out this work. Check EWRB for registered practitioners.
- Compressor or PCB (circuit board) replacement requires specialist tools and training.
For more on what work requires a licensed professional, MBIE Building Performance provides guidance on restricted building and services work.
When to Call a Professional
Call a qualified heat pump technician if:
- The error code returns after a reset and basic checks.
- The code relates to refrigerant, compressor, or electrical faults.
- The unit is making unusual noises (grinding, hissing, or banging).
- You notice ice build-up that doesn't clear after a defrost cycle.
- The unit runs but doesn't heat or cool effectively.
- You're unsure what the code means and can't find your manual.
A licensed heat pump installer or refrigeration technician can diagnose the fault accurately using specialist equipment. Attempting repairs beyond your skill level can void your warranty, cause further damage, or create a safety hazard. You can find qualified local heat pump installers on tradedirectory.co.nz.
Safety note: Never operate a heat pump that is sparking, emitting a burning smell, or showing signs of electrical damage. Switch it off at the switchboard immediately and call a professional. For electrical emergencies, contact your lines company or call 111.
Healthy Homes and Rental Properties
If you're a landlord, note that under the Healthy Homes Standards, heating appliances must be in good working order. A persistently faulting heat pump in a rental property needs prompt attention to meet your legal obligations.
ISO 9001
