Daikin Mini-Split Code L3
Soft lockout
Electrical box temperature rise. With the compressor off, the radiation fin sensor in the outdoor electrical box read too high (about 208 to 252F depending on class), so the control shut things down to protect the electronics.
Manual wording: “L3 Electrical box temperature rise”
Documented for: RKS/RXS pair outdoor units, FTXM-W/V outdoor units
Likely causes, most common first
- Defective outdoor fan motor
- Short circuit (hot discharge air recirculating into the unit)
- Defective radiation fin thermistor
- Disconnection of connector
- Defective outdoor unit PCB
What you can safely check yourself
- Check the outdoor unit has clear space around it and is not enclosed or crowded by fencing or plants
- Check the outdoor coil is not blocked with debris
- Turn the system off at the breaker or disconnect switch and back on once
When to call a technician
If the outdoor unit has proper clearance and L3 persists, the outdoor fan motor, the fin thermistor or the board needs a technician.
A Daikin mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Sources
- Service Manual - Inverter Pair FTXS-L Series / FDXS-L Series (SiUS091133) (Daikin, FTXS09/12/15/18/24/30/36LVJU wall mount, FDXS09/12LVJU ducted, RKS/RXS09-36LVJU outdoor) · checked 2026-08-25
- Service Manual - Inverter Pair Wall Mounted Type H-Series (SiUS04-924_A) (Daikin, FTXS30/36HVJU indoor, RKS30/36HVJU and RXS30/36HVJU outdoor) · checked 2026-08-25
- Service Manual - Inverter Pair Wall Mounted Type FTXM-W/V Series (SiUS042113EA) (Daikin, FTXM-W / FTXM-V (Daikin Atmosphera) wall-mount heat pump) · checked 2026-08-25