12-2
TROUBLESHOOTING
SM TRIO52 1-A.2 GB
1.2 Checking the Refrigeration System
Checking system pressures and other thermodynamic measures should be done when system is in Test Mode
(in Test mode, system operates in fixed settings). The performance curves given in this manual are given for
unit performance in test mode when high indoor fan speed is selected.
Entering test mode:
Set the two indoor units to Cool/16 degrees/High indoor fan speed, or Heat/30 degrees/High indoor fan speed,
and enter diagnostics. Note: the two indoor units should be set to the same mode and fan speed.
1.3 Judgment by MSMP Diagnostics
The MSMP controller has 9 LED’s (4 green Unit LEDs and 5 red Status/Fault LEDs). For the 4 green Unit
LEDs,O-Outdoor unit, A-Indoor unit 1,B-Indoor unit 2,C-Indoor unit 3. For the 5 red Status/Fault LEDs, it should
be read from O-A-B-C-D to get fault numbers. The 4 green Unit LEDs will turn on one at a time and the
corresponding Indoor/Outdoor unit status/fault code will be displayed on the red Status/Fault LEDs. If the unit is
normal (no fault), the green unit LED and the corresponding status will be displayed for 5 seconds and move to
the next green unit LED. On the other hand, if the unit is in fault, the green unit LED and the corresponding fault
will be displayed for 10 seconds, and hence more time to read the fault code.
STBY LED is ON when power is ON.
1.3.1 MSMP Fault Code for Outdoor unit:
No
Problem
5
4
3
2
1
Possible reason
Corrective Action
1
OCT is disconnected
0 0 0 0 1
1.OCT is not
connected to controller
terminal;
2.OCT is cut out;
3.Controller is
damaged
In case1, reinstall OCT and make sure it’s
connected well; If fault still exists, move to
check case2, use a multimeter to check
OCT’s resistor, if it’s +
, OCT is damaged
and change a new one; if it’s around10K(at
25 ), then move to case 3; In case 3, change
a new controller.
2
OCT is shorted
0 0 0 1 0
1.OCT is
shorted;
2.Controller is shorted
In case 1, use a multimeter to check OCT’s
resistor, if it’s 0, OCT is damaged and change
a new one; if it’s around 10K(at 25 ), then
move to case 2; In case 2, change a new
controller.
3
CTT is disconnected
0
0
0
1
1
Similar as item 1
Similar as item 1
4
CTT is shorted
0
0
1
0
0
Similar as item 2
Similar as item 2
5
HST is disconnected
(when enabled)
0
0
1
0
1
Similar as item 1
Similar as item 1
6
HST is shorted (when
enabled)
0
0
1
1
0
Similar as item 2
Similar as item 2
7
OAT is disconnected
(when enabled)
0
0
1
1
1
Similar as item 1
Similar as item 1
8
OAT is shorted (when
enabled)
0
1
0
0
0
Similar as item 2
Similar as item 2
9
TSUCis disconnected
(when enabled)
0
1
0
0
1
Similar as item 1
Similar as item 1
10
TSUC is shorted (when
enabled)
0
1
0
1
0
Similar as item 2
Similar as item 2
11
IPM
0 1 0 1 1 Possibly
damaged.
Turn OFF the system. Check wiring. Wait for
3 minutes and turn ON again. If the fault still
exists, return the controller to factory and
report the fault code.
12
Bad ODU EEPROM
0 1 1 0 0 Similar as item 11.
Similar as item 11.
13
DC under voltage
0 1 1 0 1 Similar as item 11.
Similar as item 11.
14
DC over voltage
0 1 1 1 0 Similar as item 11.
Similar as item 11.
15
AC under voltage
0 1 1 1 1 Similar as item 11.
Similar as item 11.
16
IDU/ODU
Communication
mismatch
1 0 0 0 0
Possibly miss-wiring
between IDU and ODU.
Check connection between IDU and ODU.
17
No Communication
1 0 0 0 1
Possibly mis-wiring
between IDU and ODU.
Check connection between IDU and ODU.
18
Illegal ODU Model
1 0 0 1 0
ODU Model jumper
setting is wrong;
Check the jumper setting according to the
model table on the controller label
CONTENTS
