MCAC-HTSM-2012-04
R410a Full DC Inverter Mini VRF
Part 4
Troubleshooting
1. Normal Air Conditioner Phenomenon ............. 63129
2. Air Conditioner Protection in Common ................. 63
3. Malfunction Code and Troubleshooting ................ 64
Troubleshooting
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1. Normal Air Conditioner Phenomenon
1.1 When outdoor unit appears white vapor or water, the reasons is as follows:
1) The fan of outdoor unit stops to begin defrosting.
2) The electromagnet valve sends out the noise when the defrosting begins and ends.
3) There is sound like water flowing when running or off; and the noise enlarges after running for 3
minutes. This is the sound of refrigerant flowing or discharging water gathered by dehumidifying.
1.2 Outdoor units send out the noise of “pupu”, for temperature changes to heat exchanger heat
expanded or cool compact.
1.3 Indoor units send out odor smell, because it absorbs the smell of house, furniture or smoking.
1.4 The running light of indoor unit flickers, the reasons are general as follows:
1) Power supply ever failed during running period.
2) For 1-to-several, the following induces the director lighting and the operation stopping
① Other indoor units running at heating mode induce to this indoor unit cannot run at cooling mode
② Setting mode conflicts with the fixed mode.
③ Stop fan to prevent discharging cool air.
1.5 The “no priority” or “waiting” director light of operation board lights.
1.6 Auto running or stopping for the timer wrong operation.
1.7 Cannot run, the reasons are as follows:
① Power is off.
② Manual switch is pulled to off side.
③ Fuse is cut.
④ Protect device starts, at the same time running director lights.
⑤ Timer’s setting time is over, at the time running director lights.
1.8 Heating or cooling is inefficient.
① Filter is block by duct or rubbish.
② The place of air deflector is unfit.
③ Fan mode is “slight” or running mode is “fan”.
④ Setting temperature is unfit.
⑤ Simultaneously choose the heating and cooling mode, at the time the “no priority” or “waiting”
director light of panel lights.
2. Air Conditioner Protection in Common
2.1 Compressor protection.
When power is on, or machine stops then restarts right away, outdoor unit will run in 3 minutes to protect
the compressor from too frequent starts and stops.
2.2 When the protection device functions, running stops. Refer to the following:
① Forced to start but not possess the start article, and display light lights.
② When cooling running, inlet and outlet of outdoor unit are blocked, outside strong air blows into
outdoor unit’s outlet.
③ When heating running, dust adheres to air filter to block inlet or outlet of outdoor unit.
Note: When protecting, please cut manual power switch. After checking the reason and solving it, restart.
2.3 Power fails.
① If power supply fails while machine is running normally, system will record this.
② When the machine is powered on again, the running light of wire controller would flash to inform
user about this.
③ Press the on/off key of wire controller to confirm this before restart the system.
Note: When running, if system takes place mistaken operation or lighter, please pull down the power
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R410a Full DC Inverter Mini VRF
supply switch to cut it off. Before restarting machines, please press the on/off key again as above.
3. Malfunction Code and Troubleshooting
If there is phenomenon as follows, please stop air conditioner running and cut power supply and refer to
the following. However, if the problem insists, please contact the customer service center of Midea
commercial air conditioner company, and offer machine’s model and detailed malfunction.
Display
Troubleshooting
Malfunction or Protection
E0
EEPROM malfunction
E2
Communication malfunction between indoor/outdoor units
E3
Communication malfunction in outdoor PCB
E4
T3&T4 temperature sensor malfunction
E5
Outdoor unit voltage protection
E6
Dc fan motor malfunction
E7
A fan in the A region run for more than 5 minutes in Heat model
E8
There are two times E6 fault in 10 minutes (recovery after power off)
P0
Radiator high temperature protection
P1
High pressure protection
P2
Low pressure protection
P3
Compressor current protection
P4
Compressor discharge temperature protection
P5
Condenser high temperature protection
P6
IPDU modules protection
P7
Evaporator high temperature protection
P8
Typhoon protection
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3.1 "E0": EEPROM malfunction
Outdoor Unit
Display
E0
Error
Explanation
EEPROM malfunction.
Supposed
Causes
1. The EEPROM is not inserted well.
2. Outdoor main board broken.
Troubleshooting
LED indicates E0
EEPROM malfunction
Check whether the
EEPROM is inserted
well
No
Insert the EEPROM well
Yes
Replace outdoor main
board
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R410a Full DC Inverter Mini VRF
3.2 "E2": Communication malfunction between
indoor/outdoor units
Outdoor Unit
Display
E2
Error
Explanation
Communication malfunction between indoor/outdoor units
Supposed
Causes
1. Indoor unit power is off
2. The signal wiring is not shield cable or the shield cable is not earthing
3. The signal wiring between the indoor and outdoor units is wrong polarity
4. The signal wiring between the indoor and outdoor units is broken
5. Indoor or outdoor main board is broken
Troubleshooting
LED indicates E2
Communication malfunction
between indoor/outdoor units
No
Check
whether
the
indoor unit power is on
Turn on the indoor
unit power
Yes
No
Check whether the signal wiring is shield cable
or whether the shield cable is earthing
Adopt the shield cable/
shield cable earthing
Yes
Check whether the signal wiring
between the indoor and outdoor
units is wrong polarity
Check whether the signal wiring between
the indoor and outdoor units is broken
Yes
Connect the signal wiring
correctly
Yes
Replace the broken wiring
No
Indoor or outdoor main board is
broken, replace the main board until
the malfunction is disappear
Troubleshooting
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3.3 "E3": Communication malfunction in outdoor
PCB
Outdoor Unit
Display
E3
Error
Explanation
Communication malfunction in outdoor PCB
Supposed
Causes
1. The outdoor main board 2 is broken
2. The connecting wiring between the IPM module and the CN1 on the main
board 2 is break off
Troubleshooting
LED indicates E3
Communication malfunction
in outdoor PCB
Check whether the indicator lights
LED1 on the main board 2 are flashing
Yes
Replace the outdoor
main board 2
No
Check whether the connecting wiring between the IPM
module and the CN1 on the main board 2 is break off
Yes
Insert the connecting
wiring well over again
No
Disconnect the connecting wiring between the IPM
module and the CN1 on the main board2, use the
multimeter to measure the voltage between the IPM
module CN1 port’s 3 and 4 pillar, check whether it is
5V, (the third pillar on the main board labels +5V)
Yes
Replace outdoor main board 2
No
Check whether the connecting wiring
between the IPM module positive pole and
the CN12 on the power board is break off
Yes
Insert the connecting
wiring well over again
No
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R410a Full DC Inverter Mini VRF
Use the multi-meter to measure whether the
voltage between the P and the N on the power
board is between+(277V~345)V
Yes
Replace the IPM module
No
Replace the power board
Troubleshooting
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3.4 "E4": T3&T4 temperature sensor malfunction
Outdoor Unit
Display
E4
Error
Explanation
T3&T4 temperature sensor malfunction.
Supposed
Causes
1. Outdoor temp. sensors (T4/T3) are malfunction.
2. The resistance of outdoor temperature sensors(T3/T4) is wrong
Troubleshooting
LED indicates E4
T3&T4 temperature
sensor malfunction
Outdoor temp. sensors (T4/T3)
are malfunction
Check whether the wiring of the outdoor
temperature sensors (T3/T4) are break off
Yes
Connect the wiring well
No
Check whether the resistance of outdoor temperature
sensors(T3/T4) is wrong refer to the Annex 1
Yes
Replace outdoor temperature
sensors (T3/T4)
No
Replace outdoor main board
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R410a Full DC Inverter Mini VRF
3.5 "E5": Outdoor unit voltage protection
Outdoor Unit
Display
E5
Error
Explanation
Outdoor unit voltage protection.
Supposed
Causes
1. Power supply fault.
2. Power board broken.
Troubleshooting
LED indicates E5
Outdoor unit voltage protection
Check the voltage of outdoor unit
power supply, whether the voltage
between L and N is about 198-252V
No
Check the power supply
Yes
Replace the power board, then check
whether the system can run normally
Yes
Trouble is solved
No
Replace outdoor main board
Troubleshooting
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3.6 "E6": DC fan motor malfunction
Outdoor Unit
Display
E6
Error
Explanation
Direct current fan motor malfunction
Supposed
Causes
1. The wiring connected is fault.
2. Power supply voltage is not normal.
Troubleshooting
LED indicates E6
DC fan motor malfunction
No
Judge 1:Check the wiring connected
is right according the wiring diagram
Connect Wiring right according the wiring diagram
Yes
Judge 2:DC power supply voltage is normal
Check the Voltage between DC fan motors
red terminal and black terminal is 277-354V
at stand by state
Judge 3:DC fan motor power supply is
normal, Check the Voltage between DC fan
motors white terminal and black terminal
is15V at stand by state
Yes
Check the power
supply of PFC is
277-354V
Replace PFC
module
Yes
Change IPM Module
Yes
Judge 4:Outdoor unit is running
after indoor unit start 3mins later
Yes
No
Check the voltage of the fan
motor between yellow
terminal and black terminal
is more than 2.4V
Yes
Replace fan
motor
Replace main board
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R410a Full DC Inverter Mini VRF
3.7 "E7": A fan in the A region run for more than 5
minutes in Heat model
Outdoor Unit
Display
E7
Error
Explanation
A fan in the A region run for more than 5 minutes in Heat model.
Supposed
Causes
Troubleshooting
Troubleshooting
When LED indicates E7, please connect local branch company.
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3.8 "P0": Radiator high temperature protection
Outdoor Unit
Display
P0
Error
Explanation
Recovery the compressor stop three minutes later for temperature
reduced.
Supposed
Causes
Troubleshooting
LED indicates P0
Radiator high temperature protection
Stop unit and waiting for Three minutes
for temperature reduced, restart unit again.
Unit is running normally
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R410a Full DC Inverter Mini VRF
3.9 "P1": High pressure protection
Outdoor Unit
Display
P1
Error
Explanation
High pressure protection.
Supposed
Causes
1.Wiring between the high pressure switch and main control board is not
connected well or correctly.
2.The high pressure switch is broken.
3.The outdoor unit is bad ventilation.
4.The heat exchanger is dirty.
5.The refrigerant pipe is blocked.
Troubleshooting
LED indicates P1
High pressure protection
Whether the wiring between the high
pressure switch and main control board
is connected well or correctly
No
Connect it well
Yes
Whether the high pressure
switch is broken
Short connect the high pressure
switch socket, check whether the
system can run normally
Yes
Replace high pressure switch
No
Check whether the refrigerant system is ok
Yes
Check whether the outdoor ambient temperature is too high
Stop the unit
No
Check whether the outdoor unit is bad ventilation
Make the outdoor unit ventilate well
No
Check whether the heat exchanger is dirty
Clean the heat exchange
No
Troubleshooting
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R410a Full DC Inverter Mini VRF
Check whether the refrigerant pipe is blocked
Replace outdoor main board
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Drop refrigerant, then use the high
pressure nitrogen or refrigerant to
blow pipe, vacuumize and add the
refrigerant again
Troubleshooting
MCAC-HTSM-2012-04
R410a Full DC Inverter Mini VRF
3.10 "P2": Low pressure protection
Outdoor Unit
Display
P2
Error
Explanation
Low pressure protection
Supposed
Causes
1. The wiring between the low pressure switch and main control board is
not connected well or not correctly.
2. The low pressure switch is broken.
3. The outdoor ambient temperature is too low.
4. The refrigerant of the system is leakage.
5. The refrigerant pipe is blocked.
Troubleshooting
Normally the only way to deal with is to replace the main control board.
LED indicates P2
Low pressure protection
Judge 1: The wiring between the low
pressure switch and main control
board is connected well or correctly
No
Connect it well
Judge 2: Whether the low pressure switch is broken
Validate: Short connect the low
pressure switch socket, check whether
the system can run normally
Yes
Replace low pressure switch
No
Check whether the refrigerant system is ok
Judge 3: Check whether the outdoor
ambient temperature is too low
Yes
Stop the unit
No
Judge 4: The refrigerant of the system is leakage
Troubleshooting
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Validate: Connect the pressure gauge to the
gauge joint of the system, check whether
the pressure is lower than 0.15MPa
No
Judge 5: The refrigerant pipe is blocked
No
Yes
Leak hunting: charge nitrogen or
refrigerant to the system, if the
leakage is serious, there will be
distinct gas leakage “cici” sound; if
the leakage is little, use the
suds(mixture of water and abluent is
also ok, if it can make bubble) or
electronic leak detector
Drop refrigerant, then use the high
pressure nitrogen or refrigerant to
blow pipe, vacuumize and add the
refrigerant again
Replace outdoor main board
Remarks: When system appear 3 times P2 protection in 30 minutes, system will auto shut down and
display H5 malfunction, which can recover only by restarting the machine. Malfunction should be
promptly treated to avoid further damage.
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R410a Full DC Inverter Mini VRF
3.11 "P3": Compressor current protection
Outdoor Unit
Display
P3
Error
Explanation
Compressor current protection
Supposed
Causes
1.
2.
3.
4.
Troubleshooting
Normally the only way to deal with is to replace the main control board.
The outdoor ambient temperature is too high.
The outdoor unit is bad ventilation.
The heat exchanger is dirty.
The refrigerant pipe is blocked.
LED indicates P3
Compressor current protection
Judge 1: Check whether the input current of
the power supply wire is more than 30A
Yes
Check whether the refrigerant system is ok
Yes
Judge 2: Check whether the outdoor ambient temperature is too high
Stop the unit
No
Yes
Judge 3: Check whether the outdoor unit is bad ventilation
Make the outdoor unit
ventilate well
No
Yes
Judge 4: Check whether the heat exchanger is dirty
No
Judge 5: The refrigerant pipe is blocked
No
Yes
Clean the heat exchanger
Drop refrigerant, then use the high pressure
nitrogen or refrigerant to blow pipe,
vacuumize and add the refrigerant again
Replace outdoor main board
Troubleshooting
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3.12 "P4": Compressor discharge temperature
protection
Outdoor Unit
Display
P4
Error
Explanation
When compressor discharge temperature is more than 115°C, the unit will
stop, and unit runs again when compressor discharge temperature is less
than 90°C.
Supposed
Causes
1.The wiring connection is not right between compressor discharge temp.
sensor and PCB according to wiring diagrams.
2.The refrigerant is leakage.
3.The discharge temp. sensor is broken.
Troubleshooting
LED indicates P4
Compressor discharge temperature protection
Check whether the compressor discharge temp. more than 115°C ?
Yes
No
Check whether the wiring connection is right
between compressor discharge temp. sensor
and PCB according to wiring diagrams
No
Correct the wiring connection
Check whether the refrigerant is leakage
Yes
Judge: The discharge temp. sensor is broken
Yes
Stop leaking and add refrigerant
Validate: Check whether the resistance
of compressor discharge temp. sensor
is right refer to the Annex 2
No
Replace the compressor
discharge temp. sensor
Replace outdoor main board
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R410a Full DC Inverter Mini VRF
3.13 "P5": Condenser high temperature protection
Outdoor Unit
Display
P5
Error
Explanation
When condenser high temp. is more than 65°C, the unit will stop, and unit
runs again when outdoor pipe temp. less than 52°C.
Supposed
Causes
1. The temperature sensor is broken.
2. The voltage transformer of IDU is defective.
3. The heat exchanger is dirty.
4. The refrigerant pipe is blocked.
Troubleshooting
LED indicates P5
Condenser high temperature protection
Check whether the condenser temperature is more than 65°C
No
No
Check whether the resistance of condenser
temp. sensor is correct refer to the Annex 1
Replace the temperature sensor
Yes
Replace outdoor main board
Yes
Stop the unit
Judge1: The outdoor temp. is too high(more than 43℃)
No
Yes
Clean the heat exchanger
Judge 2: Check whether the heat exchanger is dirty
No
Drop refrigerant, then use the high pressure
nitrogen or refrigerant to blow pipe,
vacuumize and add the refrigerant again
Yes
Judge 3: The refrigerant pipe is blocked
No
Replace outdoor main board
Troubleshooting
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3.14 "P6": IPDU modules protection
Outdoor Unit
Display
P6
Error
Explanation
IPDU modules protection.
Supposed
Causes
1.
2.
3.
4.
DC generatrix is not lined correctly.
DC generatrix low or high voltage protection.
MCE malfunction.
Compressor’s frequency changes incorrectly.
Troubleshooting
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1.1 DC generatrix detection
1.2 Voltage check of DC generatrix
1.2.1 Check the voltage of DC generatrix, which is normal between 510V and 580V. If less , go to next step.
1.2.2 Check the rectification circuit. Find out any loose in the circuit. Moreover check the filter board, rectifier
stacks. Mind DC and AC switch on the meter while doing this.
1.2.3 If none of the above works, replace the main control board.
2 Voltage check of module
Troubleshooting
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2.1 The voltage between N and P should be 1.41times to local power supply.
2.2 The voltage between 1 and 2 should range from 510V to 580V
2.3 The resistance between 1,2,3,4,5 should be infinite. If any of them is about 0, which means the module has
already been broken down, we need to replace the module.
3 Compressor's characteristics
3.1 Measure the resistance among the compressor's U,V,W respectively. The resistance should range from 0.9 to 5
Ohms and be the same.
3.2 Measure the resistance between the compressor's U,V,W and GND respectively. The resistance should be more
or less mega-Ohms.
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R410a Full DC Inverter Mini VRF
3.3 Measure the current of the compressor's U,V,W terminal respectively, which should be more or less the same,
by e.g. current flow table clamp.They should be 4A at the frequency of 35 Hertz.
4 P6 appears after the compressor turns on with difficulties
4.1 Check the module according to step 3 first.
4.2 If the module works, make the machine standby for 4 hours with power supply, which can help heating the
refrigerant and oil adequately.
4.3 Start the fixed frequency compressor only for 3S to 5S.The great startup pressure could wash the impurity
away in the tube.
4.4 If the compressor's frequency climb to 37 Hertz or above in 2S after turning on, then there's something wrong
with the compressor. Check the compressor.
4.5 If the compressor 's current is normal, the malfunction appears on the control board. Please replace it.
5 The machine is powered on and “0” will appear for few seconds, then quantities of indoor units that have been
connected will appear if the machine is normal.
In normal situation:
LED 1: Flash in 1Hz (slowly flash) when standby
LED 1: On when running
LED 2: Off
Phenomenon A
LED 2 red ON
LED 1 green
Flashes 8 times and stops for 1S, then repeat.
Error:
Inverter module failure
Phenomenon B
LED 2 red ON
LED 1 green
Flashes 9 times and stops for 1S, then repeat.
Error:
Low voltage protection
Troubleshooting
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Here are 3 circumstances:
a) The voltage between the two electrolytic capacitors is less than 450V. The AC contactor should be picked up. If
not, there's something wrong with the main control board or the PTC resistors, which need to be replace
correspondingly.
b) Somewhere is loose in the circuit.
c) The voltage between P and N of CN12 on the main control board should range from 450V to 570V. If the
voltage between N terminal and middle terminal of CN12 is 15V while error displays, it means that the main
control board fails. Please replace the main control board.
Phenomenon C
LED 2 Red ON
LED1
Green
Flashes 10 times and stops for 1S, then repeat.
Error:
High voltage protection
Here are 2 circumstances:
6. Three-phase power supply 's voltage is more than 440V
7. Main control board fails. Please replace it.
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R410a Full DC Inverter Mini VRF
3.15 "P7": Evaporator high temperature protection
Outdoor Unit
Display
P7
Error
Explanation
Evaporator high temperature protection.
Supposed
Causes
Temperature sensor port connected is not right.
Troubleshooting
LED indicates P7
ODU's load is excess.
Adjust IDU's load or add ODU.
Refrigerant is excess.
Discharge part of the
refrigerant to normal level.
System contains nitrogen
or air.
Vacuumize the system and
refill the refrigerant.
System's liquid loop is blocked.
Clear away the block.
Compressor's power lines are short
or the port's are loose.
Check the compressor's
power lines.
Compressor is defective.
Chip is defective or
incorrectly installed.
Main control board is defective.
Troubleshooting
Measure
the
compressor
terminals'
resistance.Normally
they are 2~5Ω to each other and
infinite to earth.
Reinstall the chip or
replace it with a fine one.
Replace the main control unit.
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3.16 "P8": Typhoon protection
Outdoor Unit
Display
P8
Error
Explanation
Typhoon protection.
Supposed
Causes
Typhoon.
Troubleshooting
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Troubleshooting