What Do Flashing Lights on Your Heat Pump Mean? How to Fix It
Most of the time, when your heat pump’s flashing its light, it’s actually good news. They mean your system caught something and is trying to tell you what it is instead of just dying silently. The tricky part is that Mitsubishi, Daikin, and Panasonic all speak different languages when it comes to these codes.At Varcoe, we’ve dealt with thousands of heat pump error codes across Mitsubishi, Daikin, and Panasonic units here in Auckland, so we know what usually fixes itself and what actually needs a technician. Here’s what you need to know when this happens to your heat pump.
It’s Not Always Bad News
A flashing light could mean anything from “your filter is dirty” to “you need a refrigerant charge.” Some flashes are just normal operation.
For example, if your Panasonic heat pump is blinking and the indoor unit fan has stopped, you might just be in defrost mode. This is exactly what’s supposed to happen in winter when frost builds up on the outdoor coil. Give it a few minutes and it should resume heating.
The same goes for temporary power surges. If someone in your house flips too many switches at once, sometimes the system’s internal board trips and causes brief flashing. A simple reset often fixes this without any actual problem.
What Different Flashing Patterns Actually Mean
This is where it gets brand-specific, because Mitsubishi, Daikin, and Panasonic don’t use the same code system. That said, there are common themes:
- Steady, constant flashing usually points to something maintenance-related. Most of the time, it’s a clogged filter or a sensor picking up an airflow issue. Check if your filter needs cleaning. This is legitimately one of the most common “errors” we see, and it’s something you can fix yourself in about five minutes.
- Flashing in a specific sequence (like two flashes, pause, two flashes again) indicates a more precise fault. This is where your model number matters. A Mitsubishi heat pump with two green flashes and three red flashes is telling you there’s a communication problem with the remote control. A Daikin doing something similar might mean something entirely different.
- No lights flashing at all doesn’t always mean good news. Sometimes it means there’s a power issue. Check that your unit is properly plugged in and that you haven’t tripped a circuit breaker.
First Steps When Your Unit Starts Flashing
- Turn it off and back on. We know this sounds silly, but seriously: power cycle the system. Unplug the indoor unit from the wall outlet, wait two minutes, then plug it back in. This clears transient faults and addresses most temporary issues. If the flashing stops and your system resumes normal operation, you’re done.
- Check your filter. If the flashing returns, look at your air filter. If it’s visibly dirty or clogged, replace it. You should be doing this every 1-3 months during heavy use anyway, and a blocked filter causes all kinds of sensor problems and error codes. This simple fix solves about 30% of the service calls we get.
- Note the exact flash pattern. If the issue persists, watch and count the flashes carefully. Is it two flashes? Five flashes? Flashing fast or slow? Write this down or record a short video on your phone. When you call a technician, this detail actually gets you to the right diagnosis faster.
When to Get Your Manual Out
Every heat pump comes with a manual that decodes the specific error codes for your model. This is honestly your best resource. If you’ve lost it, search your model number online. Most manufacturers have PDF versions available on their websites.
For Mitsubishi units, codes like E0 (communication error), P5 (drain fault), or UF (sensor error) all require different responses. The same applies to Daikin and Panasonic. Your manual will tell you whether something needs immediate attention or if it’s a maintenance issue you can handle yourself.
Common Issues You Might See
| Issue Type | What’s Happening | DIY Fix? | Professional Fix Required? |
| Drain pump or condensation problems | Heat pumps produce water through condensation. Blocked drains trigger specific error codes | Yes – Check outdoor drain isn’t clogged with leaves or dirt | Sometimes – Drain pump may need servicing |
| Refrigerant or pressure issues | System flags refrigerant problems with specific error codes | No – Not a DIY fix | Yes – Requires licensed technician with proper equipment. Can damage compressor if ignored |
| Sensor faults | Temperature and humidity sensors malfunction and system flags immediately | Maybe – Try reseating sensor connection | Often – Technician needs to replace sensor |
| Communication errors | Remote not communicating with unit properly | Yes – Check remote isn’t pointed through window, remove interference from fluorescent lights or wireless devices | Rarely – Usually resolves with troubleshooting |
What Definitely Needs a Call
- Codes that won’t clear after a reset. If you’ve power-cycled the system and the error comes right back, something persistent is wrong. Call someone.
- Your unit is making unusual noises. Grinding, clicking, or compressor humming that sounds wrong isn’t a code issue. It’s something mechanical. Get it looked at.
- Your system isn’t heating or cooling even though there’s no error code. Sometimes things fail silently. If your unit is running but not actually changing the room temperature, something’s off.
- You smell something odd. A burning smell, electrical smell, or anything that just feels wrong: call immediately. This could be a safety issue.
Frequently Asked Questions (FAQs)
If my heat pump is flashing an error code but still heating/cooling the room, is it safe to leave it running?
Usually yes, but it depends on the code. Minor issues like sensor faults or communication errors won’t cause immediate harm. However, if the code relates to refrigerant pressure or compressor issues, continuing to run it could cause more damage. When in doubt, turn it off and call a technician rather than risk expensive compressor damage by ignoring a serious fault.
My heat pump shows an error code that clears when I reset it, but comes back the next day – is this something I need to worry about?
Intermittent codes that recur are worth investigating. It could indicate a loose sensor connection, a slow-developing drain blockage, or an electrical issue that trips under certain conditions. Document when it happens (during heating vs. cooling, specific temperatures, time of day) and call a technician with that information. They can often diagnose intermittent faults faster with context.
Can I use my phone to check error codes online instead of finding my physical manual?
Yes. Search your exact model number (found on the unit’s specification plate) plus “error codes” or “manual PDF.” Most manufacturers have downloadable versions on their websites. However, some codes are brand and model-specific, so make sure you’re checking the right manual for your exact unit, not a similar model.
If resetting the system clears the error but I don’t know what caused it, should I be concerned it will happen again?
Not necessarily. Transient faults (power surges, temporary sensor glitches) clear and don’t recur. However, if the same error comes back repeatedly or within a few days, it’s a persistent problem that needs professional attention. A one-time error that’s gone after reset is usually harmless; patterns are what warrant investigation.
My heat pump has an error code and I can see the remote control is in the room – could the remote be causing the communication error?
Possibly. Fluorescent lights, wireless devices, and even having the remote pointed through a window can cause communication interference. Try moving the remote away from these sources or turning it off completely. You can also operate the unit through the wall-mounted control panel if it has one. If the error clears without the remote nearby, interference was likely the culprit.
Get Help Without the Hassle
If you’re in Auckland and you’ve done the basic troubleshooting (reset, checked the filter, and noted the exact flashing pattern), give us a call on 0800 088 888.
We’ll talk you through what you’re seeing and let you know if it’s something simple or if one of our technicians needs to visit. We service all three of the major brands, so we can decode whatever your system is throwing at you.
In most cases, we can diagnose issues over the phone and get you sorted quickly. If it does need a visit, at least you’ll have the information ready so we can get straight to work instead of spending time guessing what the problem is.