Mitsubishi Electric PUHY-P250YNW-A Service Handbook page 278

[8-15 Maintenance/Inspection Schedule ]
4. Check method
(1)
Select the "Local" mode using the "Normal/Local" switching switch on the indoor unit.
When the "Normal/Local" switch is set to "Local," local operation of the units will be effective, and
only the remote ON/OFF operation (external input/system controller) will be ineffective.
If there is no external input, local operation of the units will be effective regardless of the
"Normal/Local" switch setting.
No alarm signals will be sent to the upper-level system such as a building control system,
including a system controller.
(If an error occurs during inspection, the error history will be stored on the unit only.)
(2)
Select the "OFF" mode using the MA remote controller of the indoor unit to stop the unit.
Before inspecting the unit, turn off the power to the unit as necessary.
(When the power to the outdoor unit is turned off, it is detected by the system controller as
a transmission error. This is normal.)
*Normal operation of LEV needs to be confirmed during operation.
Check that the pipe temperature after the LEV changes according to the LEV opening on the
diagnostic LED on the outdoor unit.
(3)
Check whether an error history remains on the nonvolatile memory on the indoor and outdoor units.
If an error history remains, take out the data before an error occurs, and correct the error after analyzing
the causes.
(4) Check each component based on the maintenance/inspection items described on the previous page.
If problems are found, repair the component.
(5) At the completion of inspection, delete the error history codes stored in the nonvolatile memory on the unit.
(By turning the dipswitch 2-3 on the outdoor unit from OFF to ON while the unit is powered, the history on
the outdoor unit will be deleted.) If the power to the outdoor unit is turned off for inspection, the transmission
error that was detected by the system controller will be deleted after power restoration. (All histories on the
system controller will be deleted. Wait until the inspection of all units is completed to delete the histories.
The above step is not necessary if no system controllers are connected.)
*The transmission error (detected by the system controller while the outdoor unit is under power failure
conditions) will be automatically reset when normal transmission is restored.
(6)
Select the "ON" mode using the MA remote controller of the indoor unit to operate the unit.
(7)
Select the "Normal" mode using the using the "Normal/Local" switching switch on the indoor unit.
(8) Completed
BS_08_C
79
chapter 8 -