Toshiba MMU-P0121H Service Manual page 53

Check Detected Check code
code position name
b5 Indoor Indoor outside
input alarm
b6 Indoor Indoor outside
interlock
b7 Indoor Indoor unit
No. 2 to 16 in
grouping
b9 Indoor Indoor
pressure
sensor alarm
bb Interface Discharge
temp. TD2
alarm
bd Interface Mg-SW
deposit
protective
operation
Cause
Trouble detection condition
(Position)
Alarm display By voltage Vemg to be input
by outside in outside alarm input terminal
input (Vemg < 1.25V was detected
for 60 seconds.)
Display of • By voltage value Vemg to be
outside input in outside alarm input
interlock input
terminal
(Vemg < 3.75V was
detected for 60 seconds.)
Indoor unit Server unit error in group
alarm in operating
group
operating
Indoor Indoor pressure sensor output
pressure was zero.
sensor (After judgment, operation
transmits to automatic backup
operation.)
Discharge The protective stop when
temp. (TD2) discharge temp. TD2
protection exceeded 130°C and repeats
for 3 times or more.
Fixed-speed 30 seconds passed after
Mg-SW outdoor (compressor) stops,
deposit
1 Discharge temp. 135°C for
protective
fixed-speed compressor
control is
was detected.
operating.
2 Ps pressure < 0.02MPa and
TD ≥ 60°C were detected.
3 Pd pressure ≥ 3.2MPa and
TD ≥ 80°C were detected.
[NOTE]
During control operation, if
high pressure Pd becomes
3.2MPa or more, the outdoor
fan operates.
The indoor PMV and outdoor
PMV are forcibly opened, and
the cooling cycle is formed.
3-50
Check item (Position)
• When outside equipment is connected to
connector (CN21)
1) Check outside equipment error.
2) Check indoor P.C. board error.
• When outside equipment is not
connected to connector (CN21)
1) Check indoor P.C. board.
• When outside equipment is connected to
connector (CN21)
(Indoor main P.C. board (MCC-1361)).
1) Check outside equipment error.
2) Check failure of indoor main P.C.
board (MCC-1361).
• When outside equipment is not
connected to connector (CN21)
(Indoor main P.C. board (MCC-1361)).
1) Check indoor main P.C. board
(MCC-1361).
Check each indoor unit with the remote
controller
• Check connection and wiring of connector
(CN23) of indoor pressure sensor and
indoor main P.C. board (MCC-1361).
• Check indoor pressure sensor error.
• Check failure of indoor main P.C. board
(MCC-1361).
• Check service valves.
(Gas side, Liquid side are fully open.)
• Check for blockage of outdoor PMV.
1) Refrigerant choke circuit (PMV A)
2) Cooling bypass circuit (PMV B)
3) Liquid line check valve
(Cooling only model)
• Check TD2 sensor resistance value
characteristics
• Check refrigerant shortage, piping
blockage
• Check contact of the fixed-speed Mg-SW.
• Check for refrigerant shortage.
• Check discharge temp. TD sensor error at
fixed-speed unit side.
• Check Pd and Ps pressure sensors error.