Carrier 38MBRC Series User manual

Specifications subject to change without notice.
TABLE of CONTENTS
PAGE
SAFETY CONSIDERATIONS ....................................................... 1
INTRODUCTION............................................................................ 1
MODEL / SERIAL NUMBER NOMENCLATURES .................... 2
WIRING ........................................................................................... 3
CONNECTION DIAGRAM............................................................ 4
WIRING DIAGRAMS..................................................................... 5
REFRIGERATION CYCLE DIAGRAM........................................ 7
REFRIGERANT LINES .................................................................. 8
SYSTEM EVACUATION AND CHARGING ............................... 9
SYSTEM VACUUM AND CHARGE ............................................ 9
ELECTRONIC FUNCTIONS ......................................................... 10
TROUBLESHOOTING ................................................................... 15
DIAGNOSIS AND SOLUTION...................................................... 16
DIAGNOSIS AND SOLUTION...................................................... 18
DISASSEMBLY INSTRUCTIONS ................................................ 38
DISASSEMBLY INSTRUCTIONS ................................................ 42
APPENDICIES ................................................................................ 55
SAFETY CONSIDERATIONS
Installing, starting up, and servicing air-conditioning equipment can
be hazardous due to system pressures, electrical components, and
equipment location (roofs, elevated structures, etc.).
Only trained, qualified installers and service mechanics should install,
start-up, and service this equipment.
Untrained personnel can perform basic maintenance functions such as
coil cleaning. All other operations should be performed by trained
service personnel.
When working on the equipment, observe precautions in the literature
and on tags, stickers, and labels attached to the equipment.
Follow all safety codes. Wear safety glasses and work gloves. Keep a
quenching cloth and fire extinguisher nearby when brazing. Use care
in handling, rigging, and setting bulky equipment.
Read this manual thoroughly and follow all warnings or cautions
included in the literature and attached to the unit. Consult local
building codes and National Electrical Code (NEC) for special
requirements. Recognize safety information. This is the safety-alert
symbol . When you see this symbol on the unit and in instructions
or manuals, be alert to the potential for personal injury. Understand
these signal words: DANGER, WARNING, and CAUTION.
These words are used with the safety-alert symbol. DANGER
identifies the most serious hazards which will result in severe personal
injury or death. WARNING signifies hazards which could result in
personal injury or death. CAUTION is used to identify unsafe
practices which may result in minor personal injury or product and
property damage. NOTE is used to highlight suggestions which will
result in enhanced installation, reliability, or operation.
INTRODUCTION
This service manual provides the necessary information to service,
repair, and maintain the 38MBRC family of heat pumps. Use the
“TABLE of CONTENTS” on page 1 to locate a desired topic. For
detailed information regarding product specifications refer to product
data documentation.
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury or death.
Before installing, modifying, or servicing system, main electrical
disconnect switch must be in the OFF position. There may be more than 1
disconnect switch.
Lock out and tag switch with a suitable warning label.
WA R N I N G
EXPLOSION HAZARD
Failure to follow this warning could result in
death, serious personal injury, and/or property
damage. Never use air or gases containing oxygen
for leak testing or operating refrigerant
compressors. Pressurized mixtures of air or gases
containing oxygen can lead to an explosion.
WA R N I N G
EQUIPMENT DAMAGE HAZARD
Failure to follow this caution may result in equipment damage or improper
operation.
Do not bury more than 36 in. (914 mm) of refrigerant pipe in the ground.
If any section of pipe is buried, there must be a 6 in. (152 mm) vertical rise
to the valve connections on the outdoor units. If more than the
recommended length is buried, refrigerant may migrate to the cooler
buried section during extended periods of system shutdown. This causes
refrigerant slugging and could possibly damage the compressor at start-up.
CAUTION
Service Manual
38MBRC
Outdoor Unit Single Zone Ductless System
Sizes 36 to 58

38MBRC: Service Manual
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
2
MODEL / SERIAL NUMBER NOMENCLATURES
Table 1 —Unit Sizes
SYSTEM TONS kBTUh VOLTAGE-PHASE OUTDOOR MODEL
3.00 36,000 208/230-1 38MBRCQ36AA3
4.00 48,000 208/230-1 38MBRCQ48AA3
5.00 58,000 208/230-1 38MBRCQ58AA3
OUTDOOR UNIT
38 MB RC Q 36 A A 3
38 = OUTDOOR UNIT
MB = MODEL
VOLTAGE
3 = 208/230-1-60
UNIT TYPE
R= OUTDOOR UNIT
MAXIMUM NUMBER OF FAN COIL UNITS THAT
CAN BE CONNECTED TO THE OUTDOOR UNIT
A= 1:1
NOT USED
SYSTEM TYPE
Q= HEAT PUMP
NOMINAL CAPACITY
36 - 3 TONS
48 - 4 TONS
58 - 5 TONS
15 22 V 10001
Week of Manufacture
Year of Manufacture V= ALL MODELS
Sequential Serial Number
Use of the AHRI Certified
TM Mark indicates a
manufacturer’s
participation in the
program For verification
of certification for individual
products, go to
www.ahridirectory.org.

38MBRC: Service Manual
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
3
WIRING
All wires must be sized per NEC (National Electrical Code) or CEC
(Canadian Electrical Code) and local codes.
Sizes 36-58 Recommended Connection Method for Power and
Communication Wiring
Power and Communication Wiring:
The main power is supplied to the outdoor unit. The field supplied power
wiring from the outdoor unit to the indoor unit consists of three (3) wires
and provides the power for the indoor unit. Two wires are high voltage
AC power and one is a ground wire. To minimize voltage drop, the
factory recommended wire size is 14/2 stranded with a ground.
Communication Wiring: A separate shielded stranded copper
conductor only, with a 600 volt rating and double insulated copper
wire, must be used as the communication wire from the outdoor unit
to the indoor unit.
Please use a separate shielded 16GA stranded control wire.
Table 2 — Wiring Sizes 36K - 58K
CABLE CABLE SIZE REMARKS
Communication
CABLE 16AWG 2 wire stranded shielded control wire
EQUIPMENT DAMAGE HAZARD
Failure to follow this caution may result in equipment damage
or improper operation.
Wires should be sized based on NEC and local codes.
CAUTION
EQUIPMENT DAMAGE HAZARD
Failure to follow this caution may result in equipment damage
or improper operation.
Be sure to comply with local codes while running wire from
the indoor unit to the outdoor unit.
Every wire must be connected firmly. Loose wiring may
cause the terminal to overheat or result in unit malfunction. A
fire hazard may also exist. Ensure all wiring is tightly
connected.
No wire should touch the refrigerant tubing, compressor or
any moving parts.
Disconnecting means must be provided and shall be located
within sight and readily accessible from the air conditioner.
Connecting cable with conduit shall be routed through the
hole in the conduit panel.
CAUTION

38MBRC: Service Manual
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
4
CONNECTION DIAGRAM
Fig. 1 — Connection Diagram Sizes 36K-58K
Fig. 2 — Control and Power Terminals Sizes 36K-58K
NOTES:
1. Do not use thermostat wire for any connection between indoor and outdoor units.
2. All connections between indoor and outdoor units must be as shown. The connections are sensitive to polarity and will generate a fault code.
208-230-1-60
L1 L2
FIELD POWER SUPPLY
Indoor Unit
Power Supply
Low voltage
Nonpolar RS-485
communication
208-230-1-60
Nonpolar RS-485
Low voltage
communication
Outdoor Unit
208-230-1-60
Power Supply
SHIELDED WIRE CONNECTING
OUTDOOR TO INDOOR
To Indoor Unit
Power Supply
S1 S2
L1
(1)L1 (2)L2
L2
P(S1)
GND
Q(S2)
CONNECTING CABLE
OUTDOOR TO INDOOR

38MBRC: Service Manual
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
5
WIRING DIAGRAMS
Size 36K
Fig. 3 — Wiring Diagram Size 36K
Table 3 — Wiring Diagram Size 36K Codes
CODE PART NAME
JX1 Terminal Block
COMP_TOP COMP. TOP OLP TEMP. Sensor
EEV Electronic Expansion Valve
FM1 DC Fan Motor
COMP Compressor
HEAT_Y Crankcase Heater
CT1 AC Current Detector
H-PRO High Pressure Switch
L-PRO Low Pressure Switch
SV Reversing Valve
TP COMP. Discharge TEMP. Sensor
T3 COIL TEMP. Sensor
T4 Outdoor Ambient TEMP. Sensor
HEAT_D Chassis Heater
MAIN BOARD
Y/
G
6
CN1
CT1
CN4
S2
S1
2
)
(
1
()
Output:230 VAC
Output:230 VAC
Output Intput: 230 VAC
U~V~W among
phases 0~250VAC
Input:0-5VDC
Connect to FAN
voltage among
phases 0~200VAC
Output:0-12VDC
Output:230 VACOutput:230 VAC
Output: 0-5VDC
Component in the dash line
TO INDOOR UNIT POWER SUPPLY
NOTE: Please use 2-core
shielded wire.
AUXILIARY BOARD
0-5VDC

38MBRC: Service Manual
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
6
WIRING DIAGRAMS (CONT)
Sizes 48K and 58K
Fig. 4 — Wiring Diagram Sizes 48K and 58K
Table 4 — Wiring Diagram Sizes 48K and 58K Codes
CODE PART NAME
COMP Compressor
CTI AC Current Detector
EEV Electronic Expansion Valve
DCFAN1 Outdoor DC Fan Motor
DCFAN2
HEAT_D Chassis Heater
HEAT_Y Crankcase Heater
H-PRO High Pressure Switch
L-PRO Low Pressure Switch
SV Reversing Valve
TP Comp. Discharge Temp Sensor
T3 Coil Temp. Sensor
T4 Outdoor Ambient Temp Sensor
COMP TOP COMP. Top OLP Temp Sensor
CN 15 CN 10
RED YELLOW
L-PR O
H-PR
O
P5
CN24
CN25
CN17
FAN_1
CN18
HEAT_Y
SV
BLUE
CN4
CN2
CN3
CN1
COMP
UVW
Y/G
CN6
CN9
10
CN2
U
V
W
BLUE
BLACK
RED
RED(WIHTE)
RED
BLACK
CT1
DCFAN2
DCFAN1
3
3
P6
CN3
Y/G
BLACK
CN22
BLUE
Y/G
Y/G
CN 14
COMP
TOP
XT1
L2
L1
TO INDOOR UNIT
FAN_2
(2)L2
(1)L1
XT2
P8
P7
IPM&PFC DRIVE BOARD
MAIN POWE R
SUPPLY
CN19
CN20 HEAT_D
RED
BLACK
EEV
Notes:
YELLOW
GRAY
S1
S2
2
XT3
Y/G
RED
BLACK
CN 9
T4
T3
CN 8
PAIQ I
TP
YELLOW
RED
CN 8 CN 5
BLUE/(BLACK)
BROWN
/(RED/WIHTE)
6
Input:230VAC
Output:230 V AC
-5V DC - +5V DC
Output:230 V AC
Output:230 V AC
Output:230 V AC
Input:0-5VDC
Input:0-5 VDC
Output:0-12VDC
Input:0-5VDC
Input:0-5VDC
Output:230 V AC
Input:230VAC
U~V~ W am ong phase s 0 ~250VAC
F AN _1 F AN _2
Co nnec t to F AN voltage am ong phase s 0 ~200VAC
0-5VD C
0-5VD C
NOTE: Use a 2-core
shielded wire.
C
omponent in the dash line
MAIN CONTROL BOARD
TO INDOOR COMM. BUS

38MBRC: Service Manual
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
7
REFRIGERATION CYCLE DIAGRAM
Fig. 5 — Refrigerant Cycle Diagram

38MBRC: Service Manual
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
8
REFRIGERANT LINES
General Refrigerant Line Sizing
1. The outdoor units are shipped with a full charge of R410A refrigerant. All charges, line sizing, and capacities are based on runs of 25ft. (7.6 m). For runs
over 25 ft. (7.6 m), consult the long-line applications section for the proper charge adjustments.
2. The minimum refrigerant line length between the indoor and outdoor units is 10 ft. (3 m).
3. Refrigerant lines should not be buried in the ground. If it is necessary to bury the lines, not more than 36in (914 mm) should be buried. Provide a
minimum 6in (152 mm) vertical rise to the service valves to prevent refrigerant migration.
4. Both lines must be insulated. Use a minimum of 1/2in. (12.7 mm) thick insulation. Closed-cell insulation is recommended in all long-line applications.
5. Special consideration should be given to isolating interconnecting tubing from the building structure. Isolate the tubing so vibration or noise is not
transmitted into the structure.
IMPORTANT: Both refrigerant lines must be insulated separately.
Table 5 displays the following maximum lengths allowed.
Table 5 — Piping and Refrigerant
• The charge amount listed in Table 5 is for piping runs up to 26 ft. (8 m).
• For piping runs greater than 26 ft. (8 m), add refrigerant up to the allowable length as specified in Table 6.
Long Line Applications,:
1. No change in line sizing is required.
2. Add refrigerant per Table 6.
Table 6 — Additional Charge Table Per Zone
SYSTEM SIZE 36K 48K 58K
PIPING
Min. Piping Length ft (m) 10(3) 10(3) 10 (3)
Standard Piping Length ft (m) 25(7.5) 25(7.5) 25(7.5)
Max. outdoor-indoor height difference (OU higher than IU) ft (m) 98(30) 98(30) 98(30)
Max. outdoor-indoor height difference (IU higher than OU) ft (m) 98(30) 98(30) 98(30)
Max. Piping length with no additional refrigerant charge ft (m) 26(8) 26(8) 26(8)
Max. Piping Length ft (m) 213(65) 213(65) 213 (65)
Additional refrigerant charge Oz/ft (g/m) 0.32(30) 0.32(30) 0.32(30)
(between Standard - Max piping length)
Gas Pipe (size-connection type) in (mm) 5/8(16) 5/8(16) 7/8(22)
Liquid Pipe (size-connection type) in (mm) 3/8(9.52) 3/8(9.52) 3/8(9.52)
REFRIGERANT
Refrigerant Type -- R410A R410A R410A
Charge Amount Lbs (kg) 6.72(3.05) 9.26(4.2) 10.58 (4.8)
UNIT SIZE TOTAL LINE LENGTH FT. ADDITIONAL CHARGE OZ/FT. (M)
MIN. MAX. >10-26 (3-8) >26-213 (8-65)
36-58 10 213 None 0.32

38MBRC: Service Manual
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
9
SYSTEM EVACUATION AND CHARGING
Refrigerant tubes and indoor coil should be evacuated using the
recommended deep vacuum method of 500 microns. The alternate triple
evacuation method may be used if the following procedure is followed.
Always break a vacuum with dry nitrogen.
SYSTEM VACUUM AND CHARGE
Using Vacuum Pump
1. Completely tighten the flare nuts (A, B, C, D, E). Fully open all circuits
service valves. Connect the manifold gage charge hose to the charge
port of the low side Master service valve to evacuate all circuits at the
same time (see Fig. 6).
2. Connect charge hose to vacuum pump.
3. Fully open the low side of manifold gage (see Fig. 7).
4. Start vacuum pump
5. Evacuate using the triple evacuation method.
6. After evacuation is complete, fully close the low side of manifold gage
and stop operation of vacuum pump.
7. The factory charge contained in the outdoor unit is good for up to
25ft. (8 m) of line length. For refrigerant lines longer than 25ft. (8
m), add refrigerant as specified in “Additional Charge Table Per
Zone” on page 8.
8. Disconnect charge hose from charge connection of the low side service
valve.
9. Securely tighten caps of service valves.
Fig. 6 — Service Valve
Fig. 7 — Manifold
Deep Vacuum Method
The deep vacuum method requires a vacuum pump capable of pulling a
vacuum of 500 microns and a vacuum gage capable of accurately measuring
this vacuum depth. The deep vacuum method is the most positive way of
assuring a system is free of air and liquid water (see Fig. 8).
Fig. 8 — Deep Vacuum Graph
Triple Evacuation Method
The triple evacuation method should be used. Refer to Fig. 9 and proceed
as follows:
1. Pump system down to 500 MICRONS of mercury and allow pump to
continue operating for an additional 15 minutes. Unit must maintain 500
microns or less for 30 minutes or more to ensure a dry system.
2. Close service valves and shut off vacuum pump.
3. Connect a nitrogen cylinder and regulator to system and open until
system pressure is 2 psig.
4. Close service valve and allow system to stand for 10 minutes. During
this time, dry nitrogen will be able to diffuse throughout the system
absorbing moisture.
5. Repeat this procedure as indicated in Fig. 9. System will then be free of
any contaminants and water vapor.
Fig. 9 — Triple Evacuation Method
Final Tubing Check
IMPORTANT: Check to be certain factory tubing on both
indoor and outdoor unit has not shifted during shipment.
Ensure tubes are not rubbing against each other or any sheet
metal. Pay close attention to feeder tubes, making sure wire ties
on feeder tubes are secure and tight.
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment damage
or improper operation.
Never use the system compressor as a vacuum pump.
CAUTION
Outdoor Unit Indoor Unit
Refrigerant
Service Valve
Low Side
High Side
A
B
C
D
Manifold Gage
500 microns
Low side valve High side valve
Charge hose
Charge hose
Vacuum pump
Low side valve
500
MINUTES
01234567
1000
1500
LEAK IN
SYSTEM
VACUUM TIGH
T
TOO WET
TIGHT
DRY SYSTEM
2000
MICRONS
2500
3000
3500
4000
4500
5000
CHECK FOR TIGHT, DRY SYSTEM
(IF IT HOLDS DEEP VACUUM)
EVACUATE
BREAK VACUUM WITH DRY NITROGEN
WAIT
EVACUATE
RELEASE CHARGE INTO SYSTEM
BREAK VACUUM WITH DRY NITROGEN
EVACUATE
WAIT

38MBRC: Service Manual
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
10
ELECTRONIC FUNCTIONS
Abbreviation
• T1: Indoor room temperature
• T2: Coil temperature of indoor heat exchanger middle
• T2B: Coil temperature of indoor heat exchanger outlet
• T3: Coil temperature of condenser
• T4: Outdoor ambient temperature
• T5: Compressor discharge temperature (TP)
• Td: Target temperature
Main Protection
Three Minute Delay for Compressor Restart
Less than a 1 minute delay for the initial start-up and a 3 minute delay for
subsequent starts.
Compressor Top Temperature Protection
The unit stops working when the compressor top temp. protector cuts off,
and restarts after the compressor top temp. protector resets.
Compressor Discharge Temperature Protection
When the compressor discharge temp. increases, the running frequency is
limited per the following rules:
• Compressor discharge temp. T5>239°F(115°C) for 5s, compressor
stops and restarts up until T5<194°F (90°C)
• 110<T5<239°F(115°C), decrease the frequency to the lower level
every 2 minutes.
• 221°F(105°C)<T5<230°F(110°C), keep running at the current
frequency.
• T5<221°F(105°C), no limit for frequency.
Fan Speed is Out of Control
When the indoor fan speed remains low (lower than 300RPM) for 50s,
the indoor fan shuts off and restarts 30s later. If the protection mode
engages 3 times when the fan motor restarts continuously, the unit stops
and the LED displays the failure.
When the outdoor fan speed remains low (lower than 100RPM) or too
high (higher than 1500RPM) for 60s, the unit stops and the LED displays
the failure. The malfunction clears 30s later.
Inverter Module Protection
The inverter module has a protection function for current, voltage and
temperature. If any of these protections engage, the corresponding code
displays on the indoor unit and the unit stops working.
Indoor Fan Delayed Open Function
When the unit starts up, the louver is active immediately and the indoor
fan opens 10s later. If the unit is running in the HEATING mode, the
indoor fan is controlled also by the anti-cold wind function.
Compressor Preheating Functions
Preheating Permitting Condition:
If T4<37.4°F(3°C) when the unit is first powered up within 5 seconds or
if T4<37.4°F(3°C) and the compressor has stopped for over 3 hours, the
compressor heating cable will work.
Preheating Mode:
A weak current flow through the compressor coil from the compressor
wiring terminal, then the compressor is heated without operation.
Preheating Release Condition:
If T4=41°F(5°C) or the compressor starts running, the preheating
function stops.
Condenser High Temperature T3 Protection:
• 131°F(55°C)<T3<140°F(60°C), the compressor frequency decreases
to the lower level until to F1 and then runs at F1. If
T3<129.2°F(54°C), the compressor keeps running at the current
frequency.
• T3<125.6°F(52°C), the compressor does not limit the frequency and
resumes the former frequency.
• T3>140°F(60°C) for 5 seconds, the compressor stops until
T3<125.6°F(52°C).
Evaporator Low Temperature T2 Protection:
• T2<32°F(0°C), the compressor stops and restarts when
T2=41°F(5°C).
• 32°F(0°C) ≦T2<39.2°F(4°C), the compressor frequency is limited
and decreases to the lower level
• 39.2°F(4°C)=T2<44.6°F(7°C), the compressor retains the current
frequency
• T2>44.6°F(7°C), the compressor frequency is not limited.
Operation Modes and Functions
FAN Mode
1. Outdoor fan and compressor stop
2. Temperature setting function is disabled and no setting temperature
appears.
3. Indoor fan can be set to high/med/low/auto
4. The louver operates same as in the COOLING mode.
5. Auto fan
Fig. 10 — FAN Mode
a
b
c
d
e
T1
°C
10.8
°F (6.0°C)
9°F (5.0°C)
7.2°F (4.0°C)
6°F (3.0°C)
1.8°F (1.0°C)
H
(H-L)*0.75+L
(H-L)*0.5+L
(H-L)*0.25+L
L

38MBRC: Service Manual
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
11
COOLING Mode
Outdoor Fan Running Rules
Fig. 11 — Outdoor Fan Running Rules
In the COOLING mode, the indoor fan runs all the time and the speed
can be selected as high, medium, low and auto. The indoor fan is
controlled as shown in Fig. 12.
Fig. 12 — Indoor Fan Table
The AUTO Fan function under the COOLING mode acts (see Fig. 13).
Fig. 13 —AUTO Fan function under the COOLING Mode
HEATING Mode
Outdoor Fan Running Rules
Fig. 14 — Outdoor Fan Running Rules
Indoor Fan Running Rules
When the compressor is on, the indoor fan can be set to high/med/low/
auto. And the anti-cold wind function has the priority. The indoor fan is
controlled as shown in Fig. 15.
Fig. 15 — Indoor Fan Running Rules
AUTO Fan action in HEATING mode
Fig. 16 — AUTO Fan action in HEATING mode
A DC_FAN_HI_SPD_ADD
B DC_FAN_MID_SPD_ADD
C DC_FAN_MIN_SPD_ADD
D DC_FAN_SLOW_SPD_ADD
E DC_FAN_SSLOW_SPD_ADD
28 (82.4°F)
19 (66.2°F)
17 (62.6°F)
26 (78.8°F)
25 (77°F)
23 (73.4°F)
22 (71.6°F)
20 (69°F)
A
B
C
D
E
A
DD
DD
D
D
D
D
D
D
D
D
D
D
D
_
A
A
A
A
D
D
D
D
D
D
D
DD
D
D
_
A
DD
DD
D
D
D
D
DD
D
D
D
D
P
D
_
A
A
A
A
D
D
D
D
D
DD
D
D
D
D
D
S
P
D
_
A
A
A
A
A
A
A
A
A
DD
DD
DD
DD
DD
DD
DD
DD
DD
DD
DD
Setting
Fan Speed
Actual
Fan Speed
H+(H+=H+G)
AH（=H）
B
C
M+(M+=M+Z)
D M(M=M)
E
F
L+(L+=L+D)
G L(L=L)
H
I
T1-Td °F (°C)
L
L-(L-=L-D)
H
H-（H-=H-G)
M
M-(M-=M-Z)
4.5(40.1)
3.0(37.4)
1.5(34.7)
4.5(40.1)
3.0(37.4)
1.5(34.7)
4.5(40.1)
3.0(37.4)
1.5(34.7)
a
b
c
d
6.0°C(13°F)
T1-Td
e
H
(H-L)*0.75+L
(H-L)*0.5+L
(H-L)*0.25+L
L
5.0°C(11.0°F)
4.0°C(8°F)
2.5°C(5°F)
1.0°C(2°F)
T4
E
D
C
B
A DC_FAN_HI_SPD_ADD
DC_FAN_MID_SPD_ADD
DC_FAN_MIN_SPD_ADD
DC_FAN_SLOW_SPD_ADD
DC_FAN_SSLOW_SPD_ADD
59°F(15°C)
5
5.4°F(13°C
)
53.6°F(12°C)
50°F(10°C)
6
9.8°F(21°C
)
6
6.2°F(19°C
)
64.4°F(18°C)
60.8°F(16°C)
Setting Fan
Speed
H（=H）
H+(H+=H+G)
M(M=M)
M+(M+=M+Z)
L(L=L)
L+(L+=L+D)
H-（H-=H-G)
M-(M-=M-Z)
L-(L-=L-D)
T1-Td+34.7°F(1.5°C)
L
H
M
-3
°F(-1.5°C)
-6°F(-3.0°C)
-10°F(-4.5°C)
Actual Fan
Speed
-3°F(-1.5°C)
-6°F(-3.0°C)
-10°F(-4.5°C)
-3°F(-1.5°C)
-6°F(-3.0°C)
-10°F(-4.5°C)
0°F(0.0°C)
T
1-Td+3°F(1.5°C)
L
(H+-L)*0.2+L
(H+-L)*0.4+L
(H+-L)*0.6+L
H+
(H+-L)*0.8+L
-2°F(-1°C)
-4°F(-2°C)
-6°F(-3°C)
-8°F(-4°C)
-11.0°F(-5°C)
-13°F(-6°C)
-15°F(-6.5°C)

38MBRC: Service Manual
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
12
Defrosting Mode
If any one of the following conditions are met, AC enters the DEFROSTING mode. After the compressor starts and continues to run, mark the
minimum value of T3 from the 10th minute to 15th minute as T30.
Fig. 17 — Defrosting Chart

38MBRC: Service Manual
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
13
Evaporator Coil Temperature Protection
Fig. 18 — Evaporator Coil Temperature Protection
Off: Compressor stops
Decrease: Decrease the running frequency to the lower level
Hold: Keep the current frequency
Resume: No limitation for frequency
Auto Mode
This mode can be chosen with remote controller and the setting
temperature can be changed between 62.6~86°F(17~30°C).
In AUTO mode, the machine either selects COOLING, HEATING or
FAN-Only mode according to DT (DT=T1-Ts).
The indoor fan runs in the AUTO Fan mode of the relevant mode. The
louver operates same as in relevant mode. If the machine switches mode
between heating and cooling, the compressor will continue to stop for 15
minutes and then choose a mode according to T1-Ts. If the setting
temperature is modified, the machine selects a running function once
again.
DRYING Mode
DRYING mode works the same as COOLING mode in BREEZE
speed. All protections are active and the same as that in the COOLING
mode.
Auto-Restart Function
The indoor unit is equipped with an auto-restart function, which is carried
out through an auto-restart module. In case of a sudden power failure, the
module memorizes the setting conditions before the power failure. The
unit resumes the previous operation setting (not including sleep function)
automatically after 3 minutes when power returns.
ΔT=T1-Ts Running Mode
ΔT≥2F(1 ℃)Cooling Mode
-2°F(-1 ℃)<ΔT<3(2°F1 ℃)Fan-only Mode
ΔT≤-1 ℃(-2°F) Heating Mode
TEstop
T2
Resume
Off
Decrease
TEdown
TEH2
Hold

38MBRC: Service Manual
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
14
Enquiry Information
Table 7 — Enquiry Information
ENQUIRY INFORMATION DISPLAY VALUE MEANING REMARK
T1,T2,T3,T4, T2B,TP,TH,
Targeted Frequency,
Actual Frequency
- 1F,- 1E,- 1d,- 1c,- 1b,- 1A - 25,- 24,- 23,- 22,- 21,- 20 1. All the displaying temperature is actual
value.
2. Temperature is Cno matter the remote.
3. T1,T2,T3,T4,T2B display range:- 25 ~ 70,
4. TP display range:- 20 ~ 130.
5. Frequency display range: 0 ~ 159HZ.
6. If the range, it displays the
maximum value or minimum
value.
- 19—99 - 19—99
A0,A1,A9 100,101,109
b0,b1,b9 110,111,119
c0,c1,c9 120,121,129
d0,d1,d9 130,131,139
E0,E1,E9 140,141,149
F0,F1,F9 150,151,159
Indoor fan speed/
Outdoor fan speed
0OFF
1,2,3,4 Low speed, Medium speed,
High speed, Turbo For some big capacity motors
14- FF
Actual fan speed = Display value turns to
decimal value and then multiply 10. The unit is
RPM.
For some small capacity motors the display
value is 14 - FF (hexadecimal), the
corresponding fan speed range is from 200-
2550 RPM.
EXV opening angle 0- FF Actual EXV opening value = Display value
turns to decimal value and then multiply 2.
Compressor continuous
running time 0- FF 0- 255 minutes
If the actual value exceeds the range, it
displays the maximum value or minimum
value.
Compressor stop causes 0- 99 For a detailed meaning, consult with an engi-
neer Decimal display
Reserve 0- FF

38MBRC: Service Manual
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
15
TROUBLESHOOTING
This section provides the required flow charts to troubleshoot problems
that may arise.
NOTE: Information required in the diagnoses can be found in
the wiring diagrams.
Required Tools:
The following tools are needed when diagnosing the units:
• Digital multimeter
• Screw drivers (Phillips and straight head)
• Needle-nose pliers
• Refrigeration gauges
Recommended Steps
1. Refer to the diagnostic hierarchy charts below and determine the
problem at hand.
2. Go to the chart listed in the diagnostic hierarchy and follow the steps in
the chart for the selected problem.
For the ease of service, the systems are equipped with diagnostic code
display LED's on both the indoor and outdoor units. The outdoor
diagnostic display is on the outdoor unit board and is limited to very few
errors. The indoor diagnostic display is a combination of flashing LED's
on the display panel on the front of the unit. If possible always check the
diagnostic codes displayed on the indoor unit first.
The diagnostic codes for the indoor and outdoor units are listed in the
following pages.
Problems may occur that are not covered by a diagnostic code, but are
covered by the diagnostic flow charts. These problems are typical air
conditioning mechanical or electrical issues that can be corrected using
standard air conditioning repair techniques.
For problems requiring measurements at the control boards, note the
following:
1. Always disconnect the main power.
2. When possible check the outdoor board first.
3. Start by removing the outdoor unit top cover.
4. Reconnect the main power
5. Probe the outdoor board inputs and outputs with a digital multi-meter
referring to the wiring diagrams.
6. Connect the red probe to hot signal and the black probe to the ground or
negative.
7. Note that some of the DC voltage signals are pulsating voltages for
signal. this pulse should be rapidly moving at all times when there is a
signal present.
8. If it is necessary to check the indoor unit board you must start by
disconnecting the main power.
9. Next remove the front cover of the unit and then control box cover.
10. Carefully remove the indoor board from the control box, place it face
up on a plastic surface (not metal).
11. Reconnect the main power and repeat steps 5, 6, and 7.
12. Disconnect main power before reinstalling board to avoid shock hazard
and board damage.

38MBRC: Service Manual
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
16
DIAGNOSIS AND SOLUTION
Outdoor Unit Error Display
Table 8 — Diagnostic Guide for Outdoor Units
DISPLAY LED STATUS PAGE
EL01 Communication malfunction between the indoor and outdoor units Page 18
EC07 Outdoor DC fan motor malfunction/fan speed out of control Page 21
EC50 Outdoor temperature sensor error --
EC51 Outdoor EEPROM error --
EC52 Condenser coil temperature sensor (T3) malfunction Page 23
EC53 Outdoor ambient temperature sensor (T4) malfunction Page 23
EC54 Compressor discharge temperature sensor TP is on open circuit or has short circuited Page 23
EC55 Outdoor IPM module temperature sensor malfunction --
EC71 Over current failure of the outdoor DC fan motor Page 21
EC72 Lack phase failure of the outdoor DC fan motor Page 23
PC00 Inverter module (IPM) protection Page 25
PC02 Top temperature protection of compressor Page 26
PC06 Discharge temperature protection of compressor Page 27
PC08 Outdoor overcurrent protection Page 28
PC0A High temperature protection of condenser Page 29
PC0F PFC module protection Page 30
PC0L Low temperature protection of the outdoor unit Page 35
PC10 Outdoor unit low AC voltage protection Page 31
PC11 Outdoor unit main control board DC bus high voltage protection Page 31
PC12 Outdoor unit main control board DC bus high voltage protection /341 MCE error Page 31
PC30 System high pressure protection Page 32
PC31 System low pressure protection --
PC40 Communication error between the outdoor main chip and compressor driven chip Page 33
PC42 Compressor start failure of the outdoor unit --
PC43 Outdoor compressor lack phase protection Page 34
PC44 Outdoor unit zero speed protection Page 28
PC45 Outdoor unit IR chip drive failure Page 35
PC46 Compressor speed has been out of control Page 28
PC49 Compressor overcurrent failure Page 28
PH90 High temperature protection of the evaporator --
PH91 Low temperature protection of the evaporator --
LC06 High temperature protection of the inverter module (IPM) Page 26

38MBRC: Service Manual
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
17
Outdoor Unit Point Check Function
Table 9 — Outdoor Check Function
NUMBER OF
PRESSES DISPLAY REMARK
00 Normal display Displays the running frequency, running state, or malfunction code
01 Indoor unit capacity demand code
Actual data*HP*10
If the capacity demand code is higher than 99, the digital display tube displays a single digit
and a tens digit. (For example, the digital display tube displays “5.0”, which means the
capacity demand is 15. The digital display tube displays “60”, which means the capacity
demand is 6.0) GA algorithm models display “--”
02 The frequency after the capacity
requirement adapter
03 Room temperature (T1) If the temperature is lower than 0 degree, the digital display tube displays “0”. If the
temperature is higher than 70 degrees, the digital display tube displays “70”.
04 Indoor unit evaporator temperature (T2) If the temperature is lower than -9 degrees, the digital display tube displays “-9”. If the
temperature is higher than 70 degrees, the digital display tube displays “70”. If the indoor unit
is not connected, the digital display tube appears: “--”
05 Condenser pipe temp.(T3)
06 Outdoor ambient temp.(T4)
07 Compressor discharge temp. (TP)
The display value is between 0~199 degree. If the temp. is lower than 0 degree, the digital
display tube displays “0”. If the temp. is higher than 99 degrees, the digital display tube
displays a single digit and a tens digit. (For example, the digital display tube displays “0.5”,
which means the compressor discharge temperature is 105 degrees. The digital display tube
displays “1.6”, which means the compressor discharge temperature is 116 degrees.)
08 AD value of current The display value is a hex number. For example, the digital display tube shows “Cd”, which
means AD value is 205.
09 AD value of voltage
10 Indoor unit running mode code Standby:0,Cooling:1, Heating:2, Fan only 3, Drying:4, Forced cooling:6, Defrost:7
11 Outdoor unit running mode code
12 EXV open angle
Actual data/4.
If the value is higher than 99, the digital display tube displays a single digit and a tens digit. For
example, the digital display tube displays “2.0”, which means the EXV open angle is
120×4=480p.
13 Frequency limit symbol
Bit7 Frequency limit caused by IGBT radiator
The display value is a
hexadecimal number.
For example, the digital display
shows 2A, then Bit5=1, Bit3=1,
and Bit1=1.
This means that a frequency
limit may be caused by T4, T3,
or the current.
Bit6 Reserved
Bit5 Reserved
Bit4 Frequency limit caused by low
temperature of T2.(LH00)
Bit3 Frequency limit caused by T3. (LC01)
Bit2 Frequency limit caused by TP. (LC02)
Bit1 Frequency limit caused by current (LC03)
Bit0 Frequency limit caused by voltage (LC05)
14 Outdoor unit fan speed
If it is higher than 99, the digital display tube displays a single digit and a tens digit. (For
example, the digital display tube displays “2.0” which means the fan speed is 120.) This value
is multiplied by 8, and it is the current fan speed: 120*8=960
15
The average value of the temperature
values detected by the high and low
pressure sensors in the last 10 seconds
of the compressor frequency
calculation period.
The displayed value is the actual value plus 60 (that is, when the displayed value is 10, the
actual value is -50). When the displayed value is higher than 99, the digital display tube
displays a single digit and a tens digit. (If it displays 2.0, it means 120). When there is no
pressure sensor, it appears as --
16 The temperature value detected by the
high and low pressure sensor
17 AD value detected by the high and low
pressure sensor
If it is higher than 199, the digital display tube displays a single digit and a tens digit.
(For example, the digital display tube displays “2.0”, which means 220.) Otherwise, if the
temperature is higher than 99 degrees, the digital display tube displays a tens digit. (For
example, the digital display tube displays “2.0”, which means 120.) When there is no pressure
sensor, it is displayed as --
18 The currently running communication
protocol version 00-99

38MBRC: Service Manual
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
18
DIAGNOSIS AND SOLUTION
EL 01 (Indoor and Outdoor Unit Communication Error Diagnosis and Solution)
Description: Indoor unit can not communicate with outdoor unit
Recommended parts to prepare:
• Signal wires
• Magnet ring
• Indoor PCB
• Outdoor PCB
Troubleshooting and repair:
XYE Communication:
No
,
Power o

, then restart the unit 2
minutes later.
/
.
Adopt shield cable /Shield cable
earthing.
No
Yes
Correct the connection.
No
Yes
or
Remove interference or
add magnet ring on power
wire
Yes
Yes
Replace the signal wire.
Yes
Pull out and re-insert.
No
No
Replace the main PCB.
Is the error solved?
Yes
Replace the outdoor main PCB.
No
.
?
Check whether there’s any
interference.
Such as too many lamps , power
transformers. Or the signal wire
is too long .
Check whether the signal wire is
shield cable or whether the
shield cable is earthing .
Check whether the wire has the
correct polarity. P to P, Q to Q , E
to E.
Check whether the signal wire is broke.
Check whether the signal wires
are well placed on the PCB.

38MBRC: Service Manual
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
19
S Communication
NOTE: For certain models, outdoor PCB could not be removed separately. In this case, the outdoor electric control box should
be replaced as a whole.
Does the error code
disappear?
Power o , then restart the unit after 2
minutes.
Measure the DC voltage between N /L2
and S (Black pin to S , Red pin to N /L2).
The value is xed and close
to 0
The value is alternative
from negative to positive
The value is always positive
Check the wiring connection
between indoor and outdoor
unit, are they good ?
Check the wiring connection
from outdoor terminal to
outdoor PCB and wiring
between PCBs if there is
more than 1 PCB
Check the wiring connection
from indoor term inal to indoor
PCB, are they good ?
Turn on the unit , check if W
and 1(L) is connected?
Check if the power LED is on.
Yes
Yes
Yes
Unplug all the high voltage
components connected to main
PCB such as 4 way valve, heater,
AC fan one by one to check their
resistance. Is there any component
short circuit?
Unplug electronic expansion valve.
Check if power LED is on.
No
No
Check the AC voltage of L , N
output to IPM board. Is it the
same as the power input?
Check the DC 5V, 12V
from IPM board to main
PCB, are they normal?
Unplug all the high voltage
components connected to main
PCB such as 4 way valve, heater,
AC fan one by one to check their
resistance. Is there any component
short circuit?
Yes
No
Unplug electronic expansion valve.
Check if the DC 5V, 12V to main
PCB ar e OK
Replace sh ort -circuited
component and main
PCB
Replace coil of electronic
expansion valve
Replace outdoor PCB
Replace s hort -circuited
component and outdoor
PCB
Yes
Yes
Yes
Yes
Replace main PCBNo
Yes
No
Replace IPM board
No
Repalce indoor PCB
No
Solved
Correct the connection or
change wires
No
No
Yes
For units with main PCB and IPM board
both
For units with only one
PCB
For units
with W wire
For units without W
wire
No

38MBRC: Service Manual
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
20
REMARKS:
• Use a multimeter to test the DC voltage between the 2 port (or S or L2 port) and the 3 port (or N or S port) of the outdoor unit.
• The red pin of the multimeter connects to the 2 port (or S or L2 port) while the black pin is for 3 port (or N or S port).
• When the air conditioner is running normally, the voltage is moving alternately as positive values and negative values.
• If the outdoor unit malfunctions, the voltage has always had a positive value.
• If the indoor unit malfunctions, the voltage has always had a certain value.
• Use a multimeter to test the reactor resistance which does not connect with a capacitor.
• The normal value should be around zero ohm. Otherwise, the reactor has malfunctioned.
NOTE: Images and the values inside are for reference only. Actual condition and specific value may vary.
S and N
or
L2 and S
or
2 and 3