How to read Error Code in Mitsubishi electric Mr. SLIM Commercial package Inverter air conditioner

Users can check the error code by wired remote control and wireless remote control when the air conditioner is not working (power is still on).

To check the indoor unit with wireless remote control, first press a Check button on the remote control twice. The check symbol will appear with the number “00” flashing. Press “h” while pointing the remote control at the indoor unit receiver. If there is any anomaly, the receiver will beep with a flashing light.

The number of times the light flashes indicates an error code. Then, press the ON/OFF button to exit troubleshooting mode and check for parts with errors in the service manual.

To check with the “wired” remote control, press a Check button on the remote control twice then the “Self-check” sign will appear with the number “00” flashing. If there is any anomaly, the flashing number will change into an error code. Look for the error code in the service manual to identify the part with trouble. Then, press the ON/OFF button to exit troubleshooting mode.

To interpret indoor error code with wireless or wired remote control

1 beep and 1 flash indicate P1 code. 

The P1 code means there is something strange in the room temperature or return air temperature sensor. Technician should measure the resistance of TH1 temperature sensor at the CN20. By using a multi-meter, resistance should be somewhere around 4.3 to 9.5 kiloohms. If the abnormality is certain, the resistance should be out of range, there might be parts with a short or open circuit.

The next one is 2 beeps and 2 blinks. 

It indicates P2 or P9 code. P2 and P9 express abnormality in liquid piping sensor of the indoor unit. Technician should check and measure TH2 or TH5 sensor for its resistance at CN44. By using a multi-meter, resistance should be somewhere around 4.3 to 9.5 kiloohms. If abnormality is certain, the resistance should be out of range again, there might be parts with short circuit or open circuit.

Then comes 4 beeps and 4 blinks. 

The P4 code refers to false in drain sensor or open in the float switch joint. In this case, technician should check contacts of the float switch.

And Then there is E6. 

E6 indicates error in communication between the indoor and outdoor unit or, in certain cases, false in the heat exchanger. Technician should check the S3 transmission cable and the connecter for any loose or breaking.

U4 code refers to any open circuit or short circuit in the outdoor thermistor. 

Technician should check whether the RT thermistor is normal by using a multi-meter. After measuring the resistance, compare it with temperature graph.

Technician can download technical information on the website or contact the service center for more information.

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