Daikin SM-12-012 User manual

Service Manual SM-Inverter_(i)
Air Conditioners
Service Manual
Split Inverter
SM
-
12
-
012

Service Manual SM-Inverter_(i) 2
Inverter Air conditioning technology is today’s solution for superior comfort, higher efficiency and better energy
saving. This Service Manual will intro Daikin Inverter Residential and Light Commercial product.
INVERTER Y Series Single Split (Residential, Light Commercial)
i) INDOORS
ii) OUTDOORS
1.1 INVERTER SINGLE SPLIT
Residential (ATXN/FTXN-LV/FTXN-LV1B9 & ARXN/RXN-LV/RXN-LV1B9):
- High Quality & Efficiency Daikin DC Inverter compressor
- High Performance Daikin Inverter Controller
- 5-speed Step-less Fan operation
- New Inverter-only Remote Control
Piping Length & Elevation
Model
Max. total
piping
length
(m)
Max. height
difference
(m)
Pre-charge
for up to
piping length
(m)
Additional
charge
(g/m)
ARXN/RXN25LV1B(9) 20 10 7.5 20
ARXN/RXN30LV1B(9) 20 10 7.5 20
ARXN/RXN50LV1B(9) 30 10 7.5 20
ARXN/RXN60LV1B(9) 30 10 7.5 20
Terminal Block for outdoor:
- Equipped with 7-segment display to improve serviceability. (Excluded for ARXN/ RXN25/30LV1B(9))
- To retrieve error code & running parameters.
1.0 Introduction

Service Manual SM-Inverter_(i) 3
Disable Auto Random Restart function:
Series I Series II
To disable the auto random restart function, kindly cut off the jumper J_AUTO as highlighted in attachment.
Please be informed that after disable auto random restart, unit is not able to restart with last state memory after
power resume from failure. Unit will revert to default setting as below:
Default setting
Unit: Off
Temperature: 24°C
Fan speed: High
Mode: Cooling

Service Manual SM-Inverter_(i) 4
INDOOR BASIC FUNCTIONS
Residential and Light Commercial
- The system has 5 operating modes. The mode selection is done from indoor using handset.
- The operating modes are:
• Cool
• Heat
• Fan
• Auto
• Dry
Cool Mode:
- When Tr ≥ Ts - 1.5°C
• Comp, Indoor Fan and Outdoor Fan ON.
- When Tr ≤ Ts - 2°C
• Compressor and Outdoor Fan OFF.
Tr = Room Temperature
Ts = Set Temperature
When cooling load is too small and the room temperature still falling below compressor cut off point,
compressor will stop.
2.0 Algorithm and Control

Service Manual SM-Inverter_(i) 5
Heat Mode:
- When Ts > Tr - 1.0°C
• Comp, ID Fan and OD Fan ON.
- When Tr ≥ Ts + 1.5°C
• Compressor and Outdoor Fan OFF.
• Indoor Fan off if indoor coil ≤ 20°C.
Tr = Room Temperature
Ts = Set Temperature
When heating load is too small, and the room temperature still rising above compressor cut off point, compressor
will stop.
FAN MODE
- Only High, Medium and Low fan speeds are allowed.
- When changing cool mode to fan mode, the compressor will stop and OD fan stops based on fan OFF
control.
- Compressor only ON if the minimum stop time is > 3 minutes and the user change back to cool mode.
- Fan speed will maintain same as during fan mode.
AUTO MODE
- For heat pump only
- Mode switching point:
• Heating  Cooling
 Tr ≥ Ts + 2.5
• Cooling  Heating
 Tr ≤ Ts – 2.5
- During initial operation
• Cooling operation: Tr > Ts

Service Manual SM-Inverter_(i) 6
• Heating operation: Tr < Ts
ID-OD COMMUNICATION
- Master by outdoor unit.
- Indoor controller board will transmit signal to outdoor controller board every 0.5s. Outdoor unit will
response to indoor once the valid data is received.
- If the data communication line between indoor and outdoor disrupted for 15s continuously, compressor
will stop, OD fan stop with fan OFF timer. ID LED blinks error.
- If the communication resumes within 15s, error code is clear and compressor restarts after 3 minutes.
- If the communication does not resume after 15s, unit unable to restart and the error keep blinking.

Service Manual SM-Inverter_(i) 7
THERMISTORS IN ARXN/ RXN-LV1B(9)
FUNCTIONS OF THERMISTOR
Thermistor Functions
Discharge pipe Used for discharge superheat (SH) & EXV control.
Outdoor coil Used for defrost control. Also used for inverter current protection control in
Series II.
Outdoor air Used for defrost & outdoor fan speed control. Also used for PMV, overall
current protection & preheating operation control.
Heat sink Used for capturing heat sink temperature.
Suction pipe Used for EXV (SH) & suction pipe SH protection control in heating.
Gas pipe Used for gas pipe isothermal control in cooling. EXV opening is controlled so
that accurate cooling capacity is achieved in each room.
Liquid pipe Used for sub-cooling control in heating. Actual sub-cooling will be calculated
with liquid pipe & max. heat exchanger temperature among all rooms. EXV
opening is then adjusted to reach the target sub-cooling.

Service Manual SM-Inverter_(i) 8
MINIMUM RUN CONTROL
To prevent frequent compressor ON/OFF & to allow pressure equalization
•The compressor will be on 3 minutes stand-by after turning OFF before it is allowed to turn ON.
•OD fan OFF delay to improve pressure equalization & to prevent refrigerant from entering into
evaporator.
AUTO RESTART
-Factory pre-set.
-Allow unit to automatically resume the same operating mode it was in before a power failure.
4-WAY VALVE CONTROL
-Change over switching is only carried out during operation.
-OFF delayed is applied when the coil switches from ON to OFF.
Operating mode 4-way valve is
Heat, except for defrost ON
Cool
Dry
Defrost
OFF
DEFROST CYCLE
During defrost RXN-LV(1B/1B9)
Compressor ON
4-way valve OFF
EXV in operation room Fixed opening
EXV in operation stop room -
Outdoor fan OFF
Indoor fan OFF

Service Manual SM-Inverter_(i) 9
ATXN/FTXN-LV and ARXN/RXN-LV(1B/1B9):
DEFROST CONTROL
-Condition for entering defrost
•Compressor minimum run time – 6 minutes OR
•Compressor accumulated run time of 45 minutes if Outdoor coil < 3°C.
-Condition for terminating defrost
•OD coil > 12°C or
•Total defrost timer of 650 seconds.
OUTDOOR FAN CONTROL
-Determine from
•Compressor target rotation: higher fan speed with higher rotation.
•Outdoor air temperature.
-Cool mode: Higher fan speed with higher outdoor air temperature.
-Heat mode: Higher fan speed with lower outdoor air temperature.
-When compressor stops, fan OFF delay 30 seconds is carried out
INDOOR COIL FREEZE PREVENTION
-Only available in cooling mode.
-When the indoor coil temperature < 2°C, the compressor starts to drop the frequency.
-This protection will cut in when:
•Indoor coil temperature < 0°C for more than 180s. Compressor will stop, OD fan stop after 30s
and indoor fan can only run at lowest fan speed.
-The unit can only be restarted after 3 minutes.
-When the indoor coil temperature > 13°C, the compressor frequency will be reset based on the OD
ambient, room and set temperature.

Service Manual SM-Inverter_(i) 10
ROTATION REGULATING FUNCTIONS
* Defrost control for heat pump model only
STARTING ROTATION
STARTING CONTROL
-To avoid excessive oil discharge from compressor or to promote oil lubrication during startup.
-To prevent liquid flood back to the compressor.
-To limit starting current.
-When compressor starts to rotate from OFF to ON, compressor rotation is set to run gradually to each
upper limit at a specific timer setting.
Model Max. f
ARXN/RXN25LV1B(9) 68 Hz
ARXN/RXN35LV1B(9) 74 Hz
ARXN/RXN50LV1B(9) 90 Hz
ARXN/RXN60LV1B(9) 93 Hz
Upper limit rotation
Limit Rotation
Lower limit rotation
Target Rotation
Command Rotation
Starting Rotation
∆ T
Defrost*