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14
How to replace the PC board for service on the
Air to Air Heat Exchanger with DX Coil Unit
<Model>
MMD-VN(K)
✽✽✽
HEXE series
Note on replacing the PC board for service on the Air to Air Heat Exchanger with DX Coil Unit
Before replacing the PC board on the Air to Air Heat Exchanger with DX Coil Unit, non-volatile memory (hereinafter
referred to as EEPROM (IC503)) on it stores the important data such as the model code, the capacity code (factory
default), the group address, and the nighttime heat purge settings set automatically or manually (when installing the unit).
Follow the procedure below to replace the PC board for service on the Air to Air Heat Exchanger with DX Coil Unit. After
replacing the board, confirm the settings of the Air to Air Heat Exchanger with DX Coil Unit unit No. and the header /
follower configuration in the group. In addition, perform a test run.
<Replacement procedure>
▼
Case 1
When you can turn on the Air to Air Heat Exchanger with DX Coil Unit and can read the setting data from
the wired remote controller before you replace the board
Read the EEPROM data.
*1 (See page 202)
Ļ
Replace the PC board for service and turn the power on.
*2 (See page 202)
Ļ
Write the read EEPROM data.
*3 (See page 203)
Ļ
Reset the power supply. (for all the Air to Air Heat Exchanger with DX Coil Units (including the indoor units)
connected to the remote controller while performing group operation)
▼
Case 2
When you can neither turn on the Air to Air Heat Exchanger with DX Coil Unit nor operate the wired remote
controller due to a problem with the feeder circuit (when there is a problem with the circuit board) before you
replace the board
Replace the EEPROM (IC503). (For details, see “<EEPROM arrangement figure>” on page 203.)
Remove the EEPROM on the PC board, and then attach the EEPROM for service.
Ļ
Replace the PC board for service and turn the power on.
*2 (See page 202)
Ļ
Read the EEPROM data.
*1 (See page 202)
If the data cannot be read, go to
Case 3
.
Ļ
Replace the EEPROM (IC503). (For details, see “<EEPROM arrangement figure>” on page 203.)
Replace the EEPROM again. (Attach the EEPROM as before on the PC board for service.)
Ļ
Replace the PC board for service and turn the power on.
*2 (See page 202)
Ļ
Write the read EEPROM data.
*3 (See page 203)
Ļ
Reset the power supply. (for all the Air to Air Heat Exchanger with DX Coil Units (including the indoor units)
connected to the remote controller while performing group operation)
▼
Case 3
When you cannot read the setting data due to a problem with the EEPROM before you replace the board
Replace the PC board for service and turn the power on.
*2 (See page 202)
Ļ
Write the settings such as nighttime heat purge setting into the EEPROM based on client information.
*3 (See page 203)
Ļ
Reset the power supply. (for all the Air to Air Heat Exchanger with DX Coil Units (including the indoor units)
connected to the remote controller while performing group operation)
(MCC-1615)
431-6V-456
Summary of Contents for MD-VNK802HEXE
Page 120: ...118 11Owner s Manual Excerpt ...
Page 137: ...135 12Installation Manual Excerpt ...