Mitsubishi Electric CITY MULTI PUHY-P200YEM-A Service Handbook page 101

Symptom
4 "88" appears on re-
mote controller at
registration and
access remote
controller
Cause
[Generates at registration and confirmation]
1) Erroneous address of unit to be coupled.
2) Disconnection of transmission line of unit to be
coupled (No connection).
3) Faulty circuit board of unit to be coupled.
4) Installation miss of transmission line.
[Confirmation of different refrigerant system controller]
5) Disconnection of power source of outdoor unit to be
confirmed.
6) Disconnection of centralized control transmission
line (TB7) of outdoor unit.
7) Power supply connector (CN40) is not inserted into
centralized control transmission line in grouping
with different refrigerant system without using
MELANS.
8) More than 2 sets of power supply connector are
inserted into the centralized control transmission line
of outdoor unit.
9) In the system connected with MELANS, power
supply connector (CN40) is inserted into the
centralized control transmission line of outdoor unit.
10)Short circuit of centralized control transmission line.
a) Confirm the address of unit to be
b) Check the connection of transmission
c) Check the transmission terminal block
d) Confirm the power source of outdoor unit
e) Confirm that the centralized control
f) Confirm the voltage of centralized control
- 100 -
Checking method & countermeasure
coupled.
line.
voltage of unit to be coupled.
i) Normal if voltage is DC17 ~ 30V
ii) Check the item d) in case other than i).
to be coupled with the unit to be
confirmed.
transmission line (TB7) of outdoor unit is
not disconnection.
transmission line.
i) Normal in case of 10V ~ 30V
ii) Check the items 7) ~ 10) left in case
other than i).