HVAC Code Lookup

Fujitsu Mini-Split Code 11

Soft lockoutShown as: OPERATION lamp blinks 1 time, TIMER lamp blinks 1 time, ECONOMY lamp blinking continuously/fast

Serial communication error. At start up the indoor unit (evaporator) and outdoor unit (condenser) are not talking to each other over the communication wire, so the system will not run.

Manual wording: “Communication Error - At Start up, evaporator and condenser are not communicating.”

Documented for: RL2, RLS2, RLS3, RLS3H, RLS3Y, RLB, RLXB, RLXEH, RLF, RLF1, RGLX, RLE, LUAS1, LMAS, LZBS, LZAS, LPAS series

Likely causes, most common first

  1. Bad or loose interconnecting wiring between the panel, condenser and evaporator (wire nuts and splices are not recommended by Fujitsu)
  2. Incorrect voltage at the panel, condenser or evaporator
  3. Open, shorted, or mis-landed communication conductor
  4. Failed indoor or outdoor control PCB

What you can safely check yourself

  • Check that the breaker and the outdoor disconnect switch are both on
  • Turn the system off at the breaker for about 5 minutes, then back on, and see whether the code returns

When to call a technician

Everything past a power reset on this code is line-voltage and communication-wire work at the disconnect, condenser and indoor unit. Have a licensed technician check the wiring and voltages.

A Fujitsu mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Other Fujitsu codes