Samsung AC error codes – Indoor unit display codes

7 codes from the Samsung service manual, with what each one means and the usual causes. The code alternates on the display (e.g. C1 then 21). Older Samsung inverters show 3-digit codes like E121 - see the Samsung AR-HSF manual entries.

You can safely switch the unit off at the switch, wait 5 minutes and switch on again. Don't open the unit, touch wiring or handle gas: these checks need a trained technician.

C1 21also E1 21, E121

Room temperature sensor fault

What our technician checks

Room (return air) sensor: unplug and measure - most split ACs use 10 kΩ at 25°C (about 12.6 kΩ at 20°C, 8 kΩ at 30°C). Open or short = faulty. Check connector on the indoor PCB.

Book a technician for C1 21

C1 22also E1 22, E122

Heat exchanger sensor fault

What our technician checks

Indoor coil (pipe) sensor: unplug and measure (commonly 10 kΩ or 5 kΩ at 25°C depending on brand). Check it is clipped into the coil sensor pocket.

Book a technician for C1 22

C1 54also E1 54, E154

Indoor fan not rotating

What our technician checks

Indoor blower turns freely by hand? Blower wheel clean, not rubbing? Fan motor connector, motor supply (AC: capacitor
DC: about 310 V DC + 15 V and feedback signal).

Book a technician for C1 54