Mitsubishi Electric CITY MULTI PQRY-P200YMF-C Service Handbook page 82

Symptom
4 "88" appears on re-
mote controller at the
registration and
access remote
controller
Cause
[Generates at registration and confirmation]
1) Erroneous address of unit to be coupled.
2) Slipping off 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) Breaking of power source of heat source unit to be
confirmed.
6) Slipping off of centralized control transmission line
(TB7) of heat source 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 heat source unit.
9) In the system connected with MELANS, power
supply connector (CN40) is inserted into the
centralized control transmission line of heat source
unit.
10)Short circuit of centralized control transmission line.
a) Confirm the address of unit to be
coupled.
b) Check the connection of transmission
line.
c) Check the transmission terminal block
voltage of unit to be coupled.
i) Normal if voltage is DC17 ~ 30V
ii) Check the item d) in case other than i).
d) Confirm the power source of heat source
unit to be coupled with the unit to be
confirmed.
e) Confirm that the centralized control
transmission line (TB7) of heat source
unit is not slipped off.
f) Confirm the voltage of centralized control
transmission line.
i) Normal in case of 10V ~ 30V
ii) Check the items 7) ~ 10) left in case
–81–
Checking method & countermeasure
that other than i).