Error code
Mitsubishi Electric CMB code 3121
No approved translation for this record yet; showing the original text.
Meaning
Out-of-range outside air temperature: When the thermistor temperature of -28°C[-18°F] or below has continuously been detected for 3 minutes during heating operation (during compressor operation), the unit makes an error stop and "3121" appears on the display. (Use the OC thermistor temperature to determine when two outdoor units are in operation.) The compressor restarts when the thermistor temperature is -26°C[-15°F] or above (both OC and OS) during error stop.
Member details
Signed-in members see the LED pattern and how to read the code with the remote control on eligible records.
View details as a memberPossible causes
(1) Thermistor failure (2) Pinched lead wire (3) Torn wire coating (4) A pin on the male connector is missing or contact failure (5) Disconnected wire (6) Thermistor input circuit failure on the control board
Solution
Solution steps are not shared for faults that may be dangerous.
No do-it-yourself solution is given for this fault. For your safety, call an authorised service.
Remote technician support
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Address of this page: https://www.remfixit.com/tr/mitsubishi-electric/cmb/3121