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2. failure mode recall function – MITSUBISHI ELECTRIC Mitsubishi Split-Type User Manual

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Outline of the function
This air conditioner can memorize the abnormal condition which has occurred once.
Even though LED indication listed on the troubleshooting check table disappears, the memorized failure details can be
recalled.
This mode is very useful when the unit needs to be repaired for the abnormality which doesn't recur.

9-2. Failure mode recall function

1. Flow chart of the indoor/outdoor unit failure mode recall function

Operational procedure

Yes

(Blinks)

No

(OFF)

Yes

No

Releasing the failure mode recall function

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1. Regardless of normal or abnormal, a short

beep is emitted once as the signal is received.

Note1.Make sure to release the failure mode recall function once it's set up, otherwise the unit cannot operate properly.
2.If the abnormal condition is not deleted from the memory, the last abnormal condition is kept memorized.

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2. Blinking pattern when the indoor unit is abnormal:

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3.Blinking pattern when the outdoor unit is abnormal:

ON

OFF

Beeps

Repeated cycle

Repeated cycle

ON

OFF

No beep

Beeps

Repeated cycle

2.5-second OFF

Blinking at 0.5-
second interval

2.5-second OFF

3-second ON

Blinking at 0.5-
second interval

Beeps

Repeated cycle

2.5-second OFF

Blinking at 0.5-
second interval

No beep

Beeps

Repeated cycle

2.5-second OFF

3-second ON

Blinking at 0.5-
second interval

Repeated cycle

Beeps

Does the left lamp of OPERATION INDICATOR lamp
on the indoor unit blink at the interval of 0.5 seconds?
Blinks: Either indoor or outdoor unit is abnormal.
Beep sounds are emitted at the same timing
of the blinking of the left lamp of
OPERATION INDICATOR lamp.

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2

The cause of abnormality cannot be found because the abnormality doesn't recur.

Setting up the failure mode recall function

Before blinking, does the left lamp of OPERATION
INDICATOR lamp stay ON for 3 seconds?
Stays ON for 3 seconds (without beep):
The outdoor unit is abnormal.

The indoor unit is abnormal.
Check the blinking pattern, and refer to confirm the
abnormal point(9-2. 2.).
Make sure to check at least two consecutive blinking cycles.

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2

Turn ON the power supply.

1

While pressing both OPERATION SELECT

button and TOO COOL button on the remote controller at the same
time, press RESET button.

2

First, release RESET button.

And release the other two buttons since all LCD in operation display
section of the remote controller is displayed after 3 seconds.

Deleting the abnormal condition

1

After repairing the unit, recall the failure mode again according to

"Setting up the failure mode recall function" mentioned above.

2

Press EMERGENCY OPERATION switch so that the memorized

abnormal condition is deleted.

3

Release the failure mode recall function according to "Releasing the

failure mode recall function" mentioned above.

Repair the defective parts.

Release the failure mode recall function by the following procedures.

1

With the remote controller headed towards the indoor unit, press any button

that is not used in this failure mode recall function (e.g. TIMER button) .
OR

1

Turn OFF the power supply and turn ON it again.

2

Press RESET button of the remote controller.

Judgment of indoor/outdoor abnormality

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1

Press OPERATE/STOP(ON/OFF) button of the remote controller (the set temperature
is displayed).
With the remote controller headed towards the indoor unit, press TOO COOL or TOO
WARM button to adjust the set temperature to 24

:

.

Indoor unit is normal.
There is a possibility that the outdoor unit is abnormal.
Confirm the presence of abnormality according to the flow chart of the
detailed outdoor unit failure mode recall function.

The outdoor unit is abnormal.
Check the blinking pattern, and refer to confirm the abnormal point.
Make sure to check at least two consecutive blinking cycles.

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3

1

While pressing both OPERATION SELECT

button and TOO COOL button on the

remote controller at the same time,

press RESET button.

2

First, release RESET button.

And release the other two buttons since all LCD
in operation display section of the remote controller
is displayed after 3 seconds.

As for outdoor unit MUZ type, refer to service manual OB379.
As for outdoor unit MXZ type, refer to service manual OB377.

OB378_--1qxp 05.1.17 12:55 Page 12

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