Mitsubishi Electric MUZ-HA VF Series Service Manual page 27

10-2. FAILURE MODE RECALL FUNCTION
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 (10-4.) disappears, the memorized failure details can
be recalled.
1. Flow chart of failure mode recall function for the indoor/outdoor unit
Operational procedure
The cause of abnormality cannot be found because the abnormality does not recur.
Setting up the failure mode recall function
Turn ON the power supply.
<Preparation of the remote controller>
While pressing OPERATION SELECT button and TOO COOL button on the remote
controller at the same time, press RESET button.
First, release RESET button.
Hold down the other 2 buttons for another 3 seconds. Make sure that the indicators
on the LCD screen shown in the right figure are all displayed. Then release the
buttons.
Press OFF/ON (stop/operate) button of the remote controller (the set temperature is
displayed) with the remote controller headed towards the indoor unit. *1
Does 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 is emitted at the same timing as the
blinking of left lamp (HR25/35/42/50) or
upper lamp (HR60/71) of OPERATION
INDICATOR lamp. *2
Judgment of indoor/outdoor abnormality
Before blinking, does left lamp (HR25/35/42/50) or upper
lamp (HR60/71) of OPERATION INDICATOR lamp stay
ON for 3 seconds?
Stays ON for 3 seconds (without beep):
The indoor unit is abnormal.
Check the blinking pattern, and identify the abnormal point by referring to the
table of indoor unit failure mode recall function. (Refer to 10-2.2)
Make sure to check at least 2 consecutive blinking cycles. *2
Releasing the failure mode recall function
Release the failure mode recall function by the following procedures.
Turn OFF the power supply and turn it ON again.
Press RESET button of the remote controller.
Deleting the memorized abnormal condition
After repairing the unit, recall the failure mode again according to "Setting up the failure mode recall
function" mentioned above.
Press OFF/ON (stop/operate) button of the remote controller (the set temperature is displayed) with
the remote controller headed towards the indoor unit.
Press the emergency operation switch so that the memorized abnormal condition is deleted.
Release the failure mode recall function according to "Releasing the failure mode recall function"
mentioned above.
NOTE: 1. Make sure to release the failure mode recall function after it is 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.
*2. Blinking pattern when the indoor unit is abnormal:
Blinking at 0.5-
second interval
2.5-second OFF
ON
OFF
Repeated cycle
*3. Blinking pattern when the outdoor unit is abnormal:
2.5-second OFF
ON
OFF
OBH822H
*1 Regardless of normal or abnormal condition, a short
beep is emitted once the signal is received.
Yes
(Blinks)
The outdoor unit is abnormal.
No
Repair the failure parts.
Blinking at 0.5-
second interval
2.5-second OFF
Beeps Beeps
Repeated cycle
Blinking at 0.5-
3-second ON second interval
No beep Beeps
Repeated cycle
Indoor unit is normal.
But the outdoor unit might be abnormal because there are some abnor-
malities that cannot be recalled with this way.
No
Check if outdoor unit is abnormal according to the detailed outdoor unit
(OFF)
failure mode recall function.
NOTE: It takes up to 1 minute to indicate the outdoor unit abnormality.
Even if the OPERATION INDICATOR lamp is not lit, keep check-
ing at least 1 minute or longer.
Yes
The outdoor unit is abnormal.
Check the blinking pattern, and identify the abnormal point by referring
to the table of outdoor unit failure mode recall function. (Refer to outdoor
unit service manual.)
Make sure to check at least 2 consecutive blinking cycles. *3
Beeps
Repeated cycle
2.5-second OFF 3-second ON
No beep
Repeated cycle
27
Blinking at 0.5-
second interval
Beeps
Repeated cycle