MITSUBISHI ELECTRIC P500YMF-C - Manual (Page 82)

–80–
Symptom Cause
3 “HO” display on re-
mote controller does
not disappear and
ON/OFF switch is
ineffective. (Without using MELANS)
1) Outdoor unit address is set to “00”
2) Erroneous address.
1 Address setting of indoor unit to be coupled with remote controller incorrect.
(Indoor unit = remote controller - 100.)
2 Address setting of remote controller incorrect.
(Remote controller = indoor unit + 100.)
3) Faulty wiring of transmission terminal block TB5 of indoor unit in the same group with remote
controller.
4) Centralized control SW2-1 of outdoor unit is turned ON.
5) Setting to interlocking system from indoor unit (Switch 3-1 = OFF), while Fresh Master is intended to
be use by remote controller operation (indoor unit attribute).
6) Disconnection or faulty wiring of indoor unit transmission line.
7) Disconnection between indoor unit M-NET transmission line terminal block (TB5) and connector
CN2M.
8) More than 2 sets of power supply connector (CN40) are inserted into centralized control transmis-
sion line of outdoor unit.
9) Faulty outdoor unit control circuit board.
10)Faulty indoor controller board.
11)Faulty remote controller.
(Interlocking control with MELANS)
12)No grouping registration from MELANS (Neglecting to set the relation between indoor unit and
network remote controller).
13)Disconnection of centralized control transmission line (TB7) at outdoor unit.
14)At system connected with MELANS, power supply connector (CN40) is inserted to centralized
control transmission line of outdoor unit.
Checking method & countermeasure
In case MELANS is not used
In case with MELANS used
When MELANS is used, “HO” display on the remote controller will disappear at the group registration of the indoor unit and local
remote controller.
If “HO” does not disappear after the registration, check the items 12) ~ 14) in the Cause column.
Same symptom for all
units in a single refriger-
ant system?
Check outdoor unit
address
51 ~ 100?
Check centralized
control switch SW2-1 at
outdoor unit
ON?
Faulty outdoor unit
control circuit board
Outdoor unit
address set-
ting miss
Switch setting
miss
Change from
ON to OFF
Address setting
miss of remote
controller
Indoor address
setting miss
Transmission line
wiring miss of in-
door unit M-NET
Disconnection
of CN2M
connector
Setting miss of
Fresh Master
SW3-1
Repair spot
in trouble
Confirm address of remote
controller with “HO” displayed
Indoor unit + 100?
Check address of
coupling indoor unit
Remote controller
-100?
Check voltage of indoor unit M-
NET transmission terminal block
17 ~ 30V?
Check connection between indoor unit M-NET trans-
mission terminal block (TB5) and connector CN2M
Disconnection
Check Fresh Master SW3-1
Faulty indoor controller board
or remote controller
ON?
NO
NO
NO
YES
YES
YES
NO
YES
YES
YES
YES
NO
NO
NO
NO
YES