Daikin Error Code L5: Inverter Output Overcurrent (Meaning, Causes, Fixes)
What the code means
Daikin's service manuals describe L5 the same way across many models: an output overcurrent is detected by checking the current that flows in the inverter DC section, and the unit stops operating. On the newer R-32 models (for example the Perfera FTXM-A/RXM-A manual and the RXP-L2V1B manual ESIE18-01) it is listed as L5-00 and needs a manual reset from the remote. On the older B Series (SkyAir) manual, the board also counts compressor position-signal and speed errors while running; the system shuts down if the error occurs 16 times, and the count clears after about 5 minutes of normal running. Daikin's Simple Self-Diagnosis code list gives the causes as a defective compressor coil (such as a disconnected wire or insulation failure), a compressor that fails to start (mechanical lock), or a defective inverter board.
Likely causes
- A compressor problem: a shorted or poorly insulated motor winding, or a compressor that is mechanically locked and can't start.
- Loose, damaged or wrongly connected compressor wiring between the inverter board and the compressor terminals.
- A refrigerant circuit problem that overloads the compressor: a stop (service) valve left closed after installation, a clogged circuit, an overcharge or shortage of refrigerant, or moisture or air (non-condensables) in the system.
- A power supply problem: low or unstable voltage, a voltage drop, or a short circuit.
- A failed power transistor or power module on the inverter board, or a faulty main/inverter PCB.
- On some newer models, thermal grease missing or badly applied between the inverter board and its heat sink (Daikin lists this as a check).
Safe DIY checks
Turn off the breaker and outdoor disconnect before anyone opens the outdoor unit, and wait at least 10 minutes: Daikin says the inverter's rectifier can hold a dangerous voltage until it drops below 10 V DC. Compressor, inverter and refrigerant work (including mildly flammable R-32) must be done by a certified technician.
- Write down the full code (L5 or L5-00), when it happens (right at start-up or after running a while) and whether there was a storm or power outage. That helps the technician.
- Turn the system off with the remote, switch off the breaker or outdoor disconnect, wait at least 10 minutes and turn it back on. Newer Daikin models need this kind of manual reset after L5.
- Check that the outdoor unit isn't buried in snow, leaves or debris and has clear airflow around it.
- If the system was just installed or serviced, call the installer right away: Daikin lists a closed stop valve and incorrect refrigerant charge as causes of L5.
- If L5 comes back, stop resetting it and call a licensed HVAC technician. Repeated restarts against an overcurrent fault can finish off a struggling compressor or inverter board, and the remaining checks involve high voltage and refrigerant.
🛠 When to call a pro
- Work through Daikin's check order for the specific model. The Perfera FTXM-A/RXM-A manual lists: stop valves open, circuit not clogged, correct charge (no over- or undercharge), no non-condensables or moisture, main PCB, compressor (including miswiring of the compressor power cable), power supply within nominal voltage ±4%, and heat sink thermal grease.
- Check the compressor: measure winding resistance between U, V and W and insulation resistance to ground, and confirm the compressor isn't mechanically locked.
- Inspect the compressor harness and terminals on the inverter board for loose, burnt or swapped connections.
- Check supply voltage at the outdoor unit under load, and for voltage drops or short circuits.
- Check the inverter board and power module per the service manual before replacing the board; on older B Series units Daikin lists a defective power transistor, wrong internal wiring and defective PCB among the supposed causes.
- Daikin warns to wait at least 10 minutes after turning off the breaker, until the rectifier voltage is below 10 V DC, before touching the inverter board.
Parts that commonly fix it
Always match the part number to your exact model.
Multimeter / insulation tester
For checking compressor winding resistance, insulation and supply voltage, the core L5 checks.
Search eBay →Outdoor inverter control board
Daikin lists a defective inverter PCB as a cause; match the outdoor model number and have the compressor tested first.
Search eBay →Refrigerant leak detector
For a technician checking the refrigerant charge problems Daikin lists for L5.
Search eBay →Sources
- Daikin Simple Self-Diagnosis by Malfunction Code: L5 Inverter instantaneous overcurrent (DC output) (defective compressor coil, compressor startup failure from mechanical lock, defective inverter PCB)
- Daikin Perfera FTXM-A/RXM-A service manual, 3.5.26 L5-00 Outdoor unit: Inverter instantaneous overcurrent: trigger, effect, manual reset and check order
- Daikin RXP-L2V1B service manual ESIE18-01, 1.5.25 L5-00 Output over current abnormality
- Daikin B Series service manual, 4.21 Output Over Current Detection (L5): decision conditions, shutdown after 16 occurrences, supposed causes
Last reviewed 2026-10-25. Always confirm against the manual for your exact model number.