Use and Care Manual
Table Of Contents
- Foreword
 - Safety Notice
 - CONTENTS
 - Safety Notice on Maintenance
 - Safety Notice on Operation
 - 1 Product Introduction
 - NOTE: 1 Ton =12000Btu/h = 3.517kW 1.2 Electrical Parameters
 - 2 Control
 - 3 Troubleshooting
- 3.1 Wiring Diagrams
 - 3.2 PCB Layout
 - 3.3 Error Code
 - 3.4 Troubleshooting
- 3.4.1 “E1” Compressor High Pressure Protection
 - 3.4.2 “E3” Compressor Low-pressure Protection, Refrigerant Shortage Protection, Refrigerant Recovery Mode
 - 3.4.3 “E4” Compressor Air Discharge High-temperature Protection
 - 3.4.4 “F2” Condenser Temperature Sensor Error
 - 3.4.5 “F3” Outdoor Ambient Temperature Sensor Error
 - 3.4.6 “F4” Discharge Temperature Sensor Error
 - 3.4.7 “F6” ODU Tube Temperature Sensor Error
 - 3.4.8“EE” ODU Memory Chip Error
 - 3.4.9 “H4” Overload
 - 3.4.10 “H5” IPM Protection
 - 3.4.11 “H6” DC Fan Error
 - 3.4.12 “H7” Driver Out-of-Step Protection
 - 3.4.13 “HC” PFC Protection
 - 3.4.14 “Lc” Startup Failure
 - 3.4.15 “P0” Driver Reset Protection
 - 3.4.16 “P5” Over-Current Protection
 - 3.4.17 “P6” Master Control and Driver Communication Error
 - 3.4.18 “P7” Driver Module Sensor Error
 - 3.4.19 “P8” Driver Module High Temperature Protection
 - 3.4.20 “PA” AC Current Protection
 - 3.4.21 “Pc” Driver Current Error
 - 3.4.22 “PL” Bus Low-Voltage Protection
 - 3.4.23 “PH” Bus High-Voltage Protection
 - 3.4.24 “PU” Charge Loop Error
 - 3.4.25 “ee” Drive Memory Chip Error
 
 - 3.5 Failures Not Caused by Errors
 
 - 4 Maintenance
 - Appendices
 - 1 Resistance/Temperature Lists of Temperature Sensors
- 1.1 Voltage List of 15 KΩ Temperature Sensors (including ODU temperature sensors)
 - 1.2 Voltage List of 20 KΩ Pipeline Temperature Sensors (including temperature sensors for defroster, IDU and ODU pipes)
 - 1.3 Voltage List of 50 KΩ Discharge Temperature Sensors (including discharge air temperature sensor)
 
 - 2 Temperature/Pressure List of Refrigerant
 - 3 Operation Tools
 
MRCOOL DC INVERTER COOLING ONLY CONDENSING UNIT 
58 
Step 2: Disconnect power 
If  the  compressor  needs  to  be  replaced  after  judging  as  above,  then  switch  off  the  outdoor  unit  and 
disconnect the power cable of the outdoor unit. Use insulating tape to wrap the power cable and put a notice 
board on the power switch to remind people to be cautious of electric shock.   
Step 3: Neaten the electric components 
When  you  detach  the  compressor  wires,  temperature  sensors  and  electric  heaters,  mark  them 
correspondingly for the convenience of reconnecting them. 
Step 4: Discharge refrigerant 
Discharge  refrigerant  from  the  system.  Discharge  simultaneously  from  the  high  pressure  side  and  low 
pressure side. Do not discharge too fast (It should take more than 12h to completely discharge the refrigerant); 
otherwise, large quantity of lubricant will escape from the system together with the refrigerant.   
Step 5: Detach the compressor   
Check the condition of the damaged compressor, including its position and model. 
If the information of the compressor is confirmed, check the oil quality. 
(1) If the oil is clear and impurities-free, we consider that the oil of the system is not polluted. Meanwhile, if
we confirm that the valves and pipes are also normal, then we can replace the compressor only. For the
removal of compressor, please refer to the section: Removal of Major Components.
  How to check oil quality: 
1) After the compressor is detached, put it on a solid ground and shake it at an angle of 30~45° to
ensure that the contaminant at the bottom of the compressor can be poured out.
2) Place the compressor at a position above the ground level and then pour out the oil from the air
outlet of the compressor. Collect the oil in a transparent container. The amount of oil should be over
150ml.
NOTE: 
①
The axial direction of the compressor should not slant at an angle larger than 20° to the horizontal
direction.
②
Prevent the compressor from falling.
③
Put  a  transparent  container  (over  150ml  in  volume)  under  the  exhaust  pipe  to  collect  the
compressor oil, thus we can see the oil quality.
3) Put  the  container  of  compressor  lubricant  in  a  bright  location  and  see  if  there  is  impurity  and
discoloration. Sniff at the compressor lubricant. Normally, there is no pungent smell.
(2) If the oil is contaminated, replace the compressor and the gas-liquid separator.










