- F6 - cooling was limited or stopped because pressure and temperature climbed too high.
- F3 and F8 - the compressor discharge temperature is too high, or the unit is limiting operation to protect itself.
- L3 - the outdoor electrical box area got too hot.
- L4 - the outdoor inverter heat sink is too hot.
For all of them the documented homeowner response is the same: turn the system off, clean the washable indoor filters, open any blocked supply and return paths, and clear loose leaves, snow or debris from around the outdoor unit. Let it cool, then restore power once.
Two limits worth stating plainly. Do not remove panels or wash electrical parts - Daikin's guidance says clear loose debris only. And repeated F3 needs service: a compressor protecting itself once after a hot afternoon with a dirty filter is one thing; doing it again after you have cleaned everything is a fault.
The one that is not a fault at all
00 means the remote-controller code check ran and found no active malfunction code. People see two digits on a display and assume the worst - it is the opposite. If the system is heating and cooling normally, nothing needs doing. If comfort is genuinely poor and you are seeing 00, keep watching for the actual blinking indicator rather than treating 00 as the answer.
Daikin also shows several ordinary status messages: 3-minute standby (the compressor restart delay, where pressing buttons only restarts the clock), defrost, checking connection on wired controllers, the filter cleaning sign, and field setting / test run screens left over from service work.
Safe checks
- Read the display first - 00 is not a fault, and the status messages above are not either.
- Mode and setpoint - COOL, not AUTO, DRY or FAN, set below room temperature.
- Filters, then return and supply air paths indoors.
- Outdoor unit clearance and discharge side. L3 and L4 are specifically about heat building up around the outdoor unit - it needs open space to throw air, not just a clean coil.
- Multi-zone mode conflict. Daikin publishes this too: on a multi-zone system, one head calling for heat while another calls for cooling puts the non-priority head into standby. See one room won't heat or cool.
- Let it cool, then one reset - not repeated power cycling.
When to stop and call a technician
If F3, F6, F8, L3 or L4 returns after you have done the airflow work, stop repeating the cycle and call - the system is telling you the heat is not coming from a dirty filter.
Daikin publishes 61 codes in total and the rest are technician-level: sensor, inverter, communication and refrigerant faults diagnosed with instruments. Look yours up in the Daikin error-code library so you can tell the technician what the unit is reporting.
Call as well if the indoor coil ices up repeatedly, or if cooling has faded gradually over a season rather than stopping suddenly - that pattern points at charge rather than airflow, and refrigerant work is certification-gated.
Weighing repair against replacement? The installation cost estimator will size the replacement side.