Service Manual - Indoor Unit
Models: NEI32-18(37L), NEI32-24(37M), NEI32-36(37N), NEI32-48(37P), NEI32-60(37Q)
[Warning Symbol] RECOGNIZE THIS SYMBOL AS A SAFETY PRECAUTION
ATTENTION INSTALLING PERSONNEL
Prior to installation, thoroughly familiarize yourself with this Installation Manual. Observe all safety warnings. During installation or repair, caution is to be observed.
It is your responsibility to install the product safely and to educate the customer on its safe use.
Manufacturer: Eair LLC
Address: 12201 N.W. 107th Avenue, Medley, FL 33178
Website: www.comfortstarusa.com
Part 1: General Information
1 Product lineup
| Model | Capacity(Btu/h) | Appearance |
|---|---|---|
| NEI32-18 | 18000 | Illustration of a ComfortStar Floor Ceiling Indoor Unit. |
| NEI32-24 | 24000 | Illustration of a ComfortStar Floor Ceiling Indoor Unit. |
| NEI32-36 | 36000 | Illustration of a ComfortStar Floor Ceiling Indoor Unit. |
| NEI32-48 | 48000 | Illustration of a ComfortStar Floor Ceiling Indoor Unit with "INVERTER" label. |
| NEI32-60 | 55000 | Illustration of a ComfortStar Floor Ceiling Indoor Unit with "INVERTER" label. |
2 Specifications
| NEI32-18 | NEI32-24 | NEI32-36 | NEI32-48 | NEI32-60 | ||
|---|---|---|---|---|---|---|
| Indoor unit | ||||||
| Power Supply | V, Ph, Hz | 208/230V, 1Ph, 60Hz | ||||
| Cooling Capacity | Btu/h | 18000 | 24000 | 36000 | 48000 | 55000 |
| Indoor MCA | A | 1.0 | 1.0 | 1.0 | 2.45 | 2.45 |
| Indoor MFA | A | 3.0 | 3.0 | 3.0 | 3.0 | 3.0 |
| Indoor air flow | CFM | 735 | 735 | 735 | 1300 | 1300 |
| Indoor Noise level (H/L) | dB(A) | 47 | 47 | 47 | 55 | 55 |
| Communication Type | 24V / 485 | |||||
| Unpacking(W×H×D) | inch | 50-25/32×26-27/64×9-1/4 | 64-61/64×26-27/64×9-1/4 | |||
| Indoor unit Packing (W×H×D) | inch | 55-5/16×12-51/64×30-5/16 | 70-9/32×12-51/64×30-5/16 | |||
| Net/Gross Weight | lbs | 71/82 | 71/82 | 73/84 | 89/103 | 89/103 |
| Piping size | Gas side | 3/8 | 3/8 | 3/8 | 3/8 | 3/8 |
| Liquid side | 1/2 | 1/2 | 5/8 | 5/8 | 5/8 | |
| Connection wiring | 485: AWG 25*3 Shielded, 24V: AWG 20 | |||||
| Communication Type | 24V/485 | |||||
| Throttle type | Piston | Piston | Piston | Piston | Piston | |
| Cooling Operation Temp. Range | °F | 62~90 | ||||
| SERVICE CODE | 37L | 37M | 37N | 37P | 37Q | |
3 Dimensional drawings
Diagram showing dimensions for 18K/24K/36K units and 48K/60K units, with labels W (width), H (height), D (depth) for the unit, and W1, H1, D1 for the packaged unit.
| Dimensions | Model | 18K/24K/36K | 48K/60K | ||
|---|---|---|---|---|---|
| inch | mm | inch | mm | ||
| W | Indoor unit width | 50-25/32 | 1290 | 64-61/64 | 1650 |
| H | Indoor unit height | 26-27/64 | 670 | 26-27/64 | 670 |
| D | Indoor unit depth | 9-1/4 | 235 | 9-1/4 | 235 |
| W1 | Packaged width | 55-5/16 | 1405 | 70-9/32 | 1785 |
| H1 | Packaged height | 30-5/16 | 770 | 30-5/16 | 770 |
| D1 | Packaged depth | 12-51/64 | 325 | 12-51/64 | 325 |
4 Layout Functional Components
Diagram of the indoor unit showing Air Intake, Filter (Inside of Air Intake), Display Panel, Air Outlet, Vertical Louver, Horizontal Louver, and Wireless Remote Controller.
Diagram of the LED Display panel showing: Run Indicator (Red), Refrigeration Indicator (Green), Timer Indicator (Green), Heating Indicator (Yellow), Signal receiving section, Infrared receiver head, and Forced cooling switch.
6 Sound level
Diagram illustrating sound level measurement setup: an Indoor Unit with an air outlet, a ceiling, and a microphone positioned 1m away from the air outlet and 1m from the wall.
Notes:
- Sound measured at 1m away from the air outlet of the unit.
- Data is valid at free field condition.
- Data is valid at nominal operation condition.
- Reference acoustic pressure OdB = 20µPa.
- Sound level will vary depending on factors such as the construction (acoustic absorption coefficient) of the particular room in which the equipment is installed.
- The operating conditions are assumed to be standard.
| Model | Indoor Noise level (H/L) dB(A) |
|---|---|
| NEI32-18 | 47 |
| NEI32-24 | 47 |
| NEI32-36 | 47 |
| NEI32-48 | 55 |
| NEI32-60 | 55 |
Part 2: Wiring Diagram
1 Electric wiring diagram
Schematic showing the electric wiring of the indoor unit, including AC power input, transformer, various connectors (CN1, CN2, CN3, CN4, CN5, CN6, CN7, CN9, CN10, CN11, CN12, CN13, CN14, CN15, CN16, CN17, CN18, CN20, CN21, CN22, CN25, CN31, CN40, CN41, CN200), DIP switches (SW1), EEPROM, DEBUG port, RS-485 communication to outdoor unit, power input terminals, stepper motor connections, water level switch, DC pump, display panel, ambient and coil temperature sensors. Includes line annotations for factory wiring, engineering connection, physical appearance, and dashed boxes.
DIP switch status Indicate
- ON: Indicates OFF (the DIP switch is dialed to the digital side)
- OFF: Indicates ON (the DIP switch is dialed to Non-digital side)
SW1 DIP switch selection
| SW1 | Selection | Function |
|---|---|---|
| SW1.1 | OFF / ON | 24V Control |
| SW1.2 | OFF / ON | RS485 Comm. Mode |
| SW1.3 | OFF / ON | Anti-Cold Air Delay 90S / Disable Anti-Cold Air Delay |
| SW1.4 | OFF / ON | T1 from main board / T1 from thermostat |
Wire Color Code
| Color | Name |
|---|---|
| RD | RED |
| BL | BLUE |
| BR | BROWN |
| BK | BLACK |
| WH | WHITE |
| OR | ORANGE |
| GN | GREEN |
| GY | GRAY |
| YE | YELLOW |
| PR | PURPLE |
Line annotation
- Factory wiring
- Engineering connection
- Physical appearance
- Dashed box
2 PCB
Image of the Indoor Control Board with numbered ports (1-26).
| No. | Port Names and Definitions | No. | Port Names and Definitions |
|---|---|---|---|
| 1 | 220V tans in from power supply(L2) | 14 | Port for stepper motor(Floor Ceiling Unit) |
| 2 | 220V trans out (reserved) | 15 | Port for stepper motor (Cassette Unit) |
| 3 | Port for indoor fan motor | 16 | Port to wired controller |
| 4 | Port to 24V thermostat | 17 | Port to wired controller(reserved) |
| 5 | 24V trans in from transformer | 18 | Port for drainage water pump |
| 6 | Programming Port for EEPROM | 19 | Port for water level switch |
| 7 | Programming Port for debug | 20 | Port for room temperature sensor T1 |
| 8 | DIP switch | 21 | Port for coil temperature sensor T2 |
| 9 | RS-485 communication port | 22 | Reserved |
| 10 | Port to 24V thermostat | 23 | Relay for electrical heater(reserved) |
| 11 | Port to 24V thermostat | 24 | Fuse |
| 12 | Port for refrigerant concentration monitor | 25 | 220V tans in from power supply(L1) |
| 13 | Port to the panel | 26 | 220V trans out to transformer |
3 Low voltage wiring diagram
Description of low voltage wiring diagrams suitable for Indoor Unit and Outdoor Unit with 24V thermostat. Diagrams illustrate wiring for 1H and 1C, 2H and 1C, 2H and 2C, 3H and 1C, 3H and 2C, and 4H and 2C thermostat configurations (no heat pump system model). Notes explain the function of Y1/Y2 for fan operation and electric heat activation.
Control Logic:
Indoor unit connector
| Connector | Purpose |
|---|---|
| R | 24V Power Connection |
| C | Common |
| G | Fan Control |
| Y1 | Low Cooling |
| Y2 | High Cooling |
| B | Heating Reversing Valve |
| W1 | Stage1 Electrical Heating |
| W2 | Stage2 Electrical Heating |
| DH | Dehumidification |
Outdoor unit connector
| Connector | Purpose |
|---|---|
| C | Common |
| Y | Cooling |
| B | Heating Reversing Valve |
| W | Defrost Control |
Notes:
- DH wiring is optional and requires a thermostat with a humidistat. DH functions as Passive Dehumidification and will downstage the indoor fan to first stage. System will operate according to normal sequence of operations if DH wiring is absent.
- Dashed lines in the thermostat wiring diagrams refer to optional wiring (wiring for Passive Dehumidification Function and/OR Electric Heat). For thermostat wiring please refer to the Owner's Manual of the thermostat.
- B wire must be used with heat pump system only, the reversing valve energizes in heating.
4 Electrical parameters
| Capacity(Btu/h) | 18K | 24K | 36K | 48K | 60K |
|---|---|---|---|---|---|
| Power (indoor) Phase | 1 | 1 | 1 | 1 | 1 |
| Frequency and Volt | 208/230, 60Hz | ||||
| Power (outdoor) Phase | 1 | 1 | 1 | 1 | 1 |
| Frequency and Volt | 208/230, 60Hz | ||||
| Max.Fuse Indoor unit(A) | 15 | 15 | 15 | 15 | 15 |
| Max.Fuse Outdoor unit(A) | |||||
| Indoor unit Powerline Line quantity | 3 | 3 | 3 | 3 | 3 |
| Line diameter(AWG) | 16/1.5mm² | 16/1.5mm² | 16/1.5mm² | 16/1.5mm² | 16/1.5mm² |
| Outdoor unit Powerline Line quantity | 3 | 3 | 3 | 3 | 3 |
| Line diameter(AWG) | |||||
| Outdoor unit Signal line Line quantity | 3 | 3 | 3 | 3 | 3 |
| Line diameter(AWG) | 20/0.5mm² | 20/0.5mm² | 20/0.5mm² | 20/0.5mm² | 20/0.5mm² |
| Thermostat Signal line Line quantity | |||||
| Line diameter(AWG) | 18/1.0mm² | 18/1.0mm² | 18/1.0mm² | 18/1.0mm² | 18/1.0mm² |
Part 3: Diagnosis and Troubleshooting
1 Error code table
| Error code | Error definition |
|---|---|
| E1 | Outdoor unit and indoor unit communication error |
| E2 | Indoor unit T1 temperature sensor fault |
| E3 | Indoor unit T2 temperature sensor fault |
| E4 | Refrigerant concentration sensor fault (Only valid when connected to a refrigerant concentration sensor.) |
| E6 | Refrigerant leakage protection |
| E8 | Indoor fan motor current fault |
| E9 | Wired controller communication fault |
| d3 | Water level switch protection (effective only for cassette units and duct units.) |
2 Troubleshooting
2.1 Safety Precautions
The following precautions are important; follow them carefully. Read these instructions before installation. Keep this manual for future reference.
Failure to adhere to all precautionary measures listed in this section may result in personal injury, damage to the unit or property, or in extreme cases, death.
WARNING: Indicates a potentially hazardous situation which if not avoided, could result in death or serious injury.
CAUTION: Indicates a potentially hazardous situation which if not avoided, may result in minor or moderate injury. It is also used to alert against unsafe practices.
2.1.1 In case of Accidents or Emergency
WARNING:
- If a gas leak is suspected, immediately turn off the gas and ventilate the area before turning the unit on.
- If strange sounds or smoke is detected, turn the breaker off and disconnect the power supply cable.
- If the unit comes into contact with liquid, contact an authorized service center.
- If liquid from batteries makes contact with skin or clothing, immediately rinse or wash the area with clean water.
- Do not insert hands or other objects into the air inlet or outlet while the unit is plugged in.
- Do not operate the unit with wet hands.
CAUTION:
- Clean and ventilate the unit at regular intervals when operating it near a stove or similar devices.
- Do not use the unit during severe weather conditions. If possible, remove the product from the window before such occurrences.
2.1.2 Information servicing (For flammable materials)
WARNING:
- Use this unit only on a dedicated circuit.
- Damage to the installation area could cause the unit to fall, potentially resulting in personal injury, property damage, or product failure.
- Only qualified personnel should disassemble, install, remove, or repair the unit.
- Only a qualified electrician should perform electrical work. For more information, contact your dealer, seller, or an authorized service center.
CAUTION:
- While unpacking, be careful of sharp edges around the unit and the fins on the condenser and evaporator.
2.1.3 Operation and Maintenance
WARNING:
- Do not use defective or under-rated circuit breakers.
- Ensure the unit is properly grounded and that a dedicated circuit and breaker are installed.
- Do not modify or extend the power cable. Ensure the power cable is secure and not damaged during operation.
- Do not unplug the power supply plug during operation.
- Do not store or use flammable materials near the unit.
- Do not open the inlet grill of the unit during operation.
- Do not touch the electrostatic filter if the unit is equipped with one.
- Do not block the inlet or outlet of air flow to the unit.
- Do not use harsh detergents, solvents, or similar items to clean the unit. Use a soft cloth for cleaning.
- Do not touch the metal parts of the unit when removing the air filter as they are very sharp.
- Do not step on or place anything on the unit or outdoor units.
- Do not drink water drained from the unit.
- Avoid direct skin contact with water drained from the unit.
CAUTION:
- Use a firm stool or step ladder according to manufacturer procedures when cleaning or maintaining the unit.
- Do not install or operate the unit for an extended period in areas of high humidity or in an environment directly exposing it to sea wind or salt spray.
- Do not install the unit on a defective or damaged installation stand, or in an unsecured location.
- Ensure the unit is installed at a level position.
- Do not install the unit where noise or air discharge from the outdoor unit will negatively impact the environment or nearby residences.
- Do not expose skin directly to the air discharged by the unit for prolonged periods of time.
- Ensure the unit operates in areas free from water or other liquids.
- Ensure the drain hose is installed correctly to ensure proper water drainage.
- When lifting or transporting the unit, it is recommended that two or more people are used for this task.
- When the unit is not to be used for an extended time, disconnect the power supply or turn off the breaker.
2.2 E1 Troubleshooting
E1 indicates RS485 communication fault between outdoor unit and indoor unit. The unit stops running and error code is displayed on the LED display on the panel.
Flowchart:
- E1
- Communication terminals on outdoor or indoor unit have short circuit or are disconnected or misconnected. [Yes] Reconnect the communication terminals and ensure the connection is properly. [No]
- Interference from high voltage (220V or higher) wires. [Yes] Ensure the communication wires and high voltage wires are separated. [No]
- Communication wires are close to a source of electromagnetic radiation such as transformer or strong fluorescent lamp. [Yes] Remove the source of interference, or add additional shielding to the communication wires. [No]
- The communication board is damaged. [Yes] Replace the communication board (in outdoor unit electrical control box). [No]
- Replace the indoor control PCB.
2.3 E2/E3 Troubleshooting
E2 indicates indoor unit T1 temperature sensor fault. E3 indicates indoor unit T2 temperature sensor fault. The unit stops running and error code is displayed on the LED display on the panel.
Flowchart:
- E2/E3
- Temperature sensor is not installed. [Yes] Installed the temperature sensor. [No]
- Temperature sensor connection on PCB is loose. [Yes] Ensure the sensor is connected properly. [No]
- Temperature sensor is affected by moisture or water. [Yes] Dry the sensor. [No]
- Temperature sensor has short circuit or is failed. [Yes] Replace the sensor. [No]
- Replace the control PCB.
Note:
- Measure sensor resistance. If the resistance is too low, the sensor has short-circuited. If the resistance is not consistent with the sensor's resistance characteristics table, the sensor has failed.
- E2/E3 is applicable only when communication is established between the ComfortStar outdoor unit and the ComfortStar indoor unit via RS-485.
2.4 E4 Troubleshooting
E4 indicates refrigerant concentration sensor fault (Only valid when connected to a refrigerant concentration sensor.) The unit stops running and error code is displayed on the LED display on the panel.
Flowchart:
- E4
- Refrigerant concentration sensor is affected by moisture or water. [Yes] Dry the sensor. [No]
- Refrigerant concentration sensor has short circuit or is failed. [Yes] Replace the sensor. [No]
- Replace the control PCB.
Note:
- Measure sensor resistance. If the resistance is too low, the sensor has short-circuited. If the resistance is not consistent with the sensor's resistance characteristics table, the sensor has failed.
- E2/E3 is applicable only when communication is established between the ComfortStar outdoor unit and the ComfortStar indoor unit via RS-485.
2.5 E6 Troubleshooting
E6 Refrigerant leakage protection (Only valid when connected to a refrigerant concentration sensor.) The unit stops running and error code is displayed on the LED display on the panel.
Flowchart:
- E6
- Piping connection between outdoor and indoor unit is not secure. [Yes] Immediately open the door and windows for ventilation and check whether the copper pipe thread connections are tight. After ensuring that the copper pipe connections are normal, turn on the air conditioner and add refrigerant by referring to the refrigerant temperature and operating current. [No]
- Refrigerant concentration sensor has short circuit or is failed. [Yes] Replace the sensor. [No]
- Replace the control PCB.
Note:
- Measure sensor resistance. If the resistance is too low, the sensor has short-circuited. If the resistance is not consistent with the sensor's resistance characteristics table, the sensor has failed.
- E2/E3 is applicable only when communication is established between the ComfortStar outdoor unit and the ComfortStar indoor unit via RS-485.
2.6 E8 Troubleshooting
E8 indicates indoor fan motor current fault. The unit stops running and error code is displayed on the LED display on the panel.
Flowchart:
- E8
- Wires of fan are not connected properly. [Yes] Ensure wires are connected properly. [No]
- The fan motor is blocked or failed. [Yes] Remove obstruction or replace the fan motor. [No]
- The power supply is abnormal. [Yes] Check the power supply equipment. [No]
- Replace the indoor control PCB.
2.7 E9 Troubleshooting
E9 indicates wired controller communication fault. The unit stops running and error code is displayed on the LED display on the panel.
Flowchart:
- E9
- Communication terminals on wired controller or indoor unit have short circuit or are disconnected or misconnected. [Yes] Reconnect the communication terminals and ensure the connection is properly. [No]
- Interference from high voltage (220V or higher) wires. [Yes] Ensure the communication wires and high voltage wires are separated. [No]
- Communication wires are close to a source of electromagnetic radiation such as transformer or strong fluorescent lamp. [Yes] Remove the source of interference, or add additional shielding to the communication wires. [No]
- Replace the indoor control PCB.
3 Temperature Sensor Resistance Characteristics
Room temperature sensor(T1) and condenser coil temperature sensor(T2) resistance characteristics.
| Temperature (°C) | Resistance (kΩ) | Temperature (°C) | Resistance (kΩ) | Temperature (°C) | Resistance (kΩ) | Temperature (°C) | Resistance (kΩ) |
|---|---|---|---|---|---|---|---|
| -25 | 144.266 | 15 | 16.079 | 55 | 2.841 | 95 | 0.708 |
| -24 | 135.601 | 16 | 15.313 | 56 | 2.734 | 96 | 0.686 |
| -23 | 127.507 | 17 | 14.588 | 57 | 2.632 | 97 | 0.666 |
| -22 | 119.941 | 18 | 13.902 | 58 | 2.534 | 98 | 0.646 |
| -21 | 112.867 | 19 | 13.251 | 59 | 2.44 | 99 | 0.627 |
| -20 | 106.732 | 20 | 12.635 | 60 | 2.35 | 100 | 0.609 |
| -19 | 100.552 | 21 | 12.05 | 61 | 2.264 | 101 | 0.591 |
| -18 | 94.769 | 22 | 11.496 | 62 | 2.181 | 102 | 0.574 |
| -17 | 89.353 | 23 | 10.971 | 63 | 2.102 | 103 | 0.558 |
| -16 | 84.278 | 24 | 10.473 | 64 | 2.026 | 104 | 0.542 |
| -15 | 79.521 | 25 | 10 | 65 | 1.953 | 105 | 0.527 |
| -14 | 75.059 | 26 | 9.551 | 66 | 1.883 | ||
| -13 | 70.873 | 27 | 9.125 | 67 | 1.816 | ||
| -12 | 66.943 | 28 | 8.721 | 68 | 1.752 | ||
| -11 | 63.252 | 29 | 8.337 | 69 | 1.69 | ||
| -10 | 59.784 | 30 | 7.972 | 70 | 1.631 | ||
| -9 | 56.524 | 31 | 7.625 | 71 | 1.574 | ||
| -8 | 53.458 | 32 | 7.296 | 72 | 1.519 | ||
| -7 | 50.575 | 33 | 6.982 | 73 | 1.466 | ||
| -6 | 47.862 | 34 | 6.684 | 74 | 1.416 | ||
| -5 | 45.308 | 35 | 6.401 | 75 | 1.367 | ||
| -4 | 42.903 | 36 | 6.131 | 76 | 1.321 | ||
| -3 | 40.638 | 37 | 5.874 | 77 | 1.276 | ||
| -2 | 38.504 | 38 | 5.63 | 78 | 1.233 | ||
| -1 | 36.492 | 39 | 5.397 | 79 | 1.191 | ||
| 0 | 34.596 | 40 | 5.175 | 80 | 1.151 | ||
| 1 | 32.807 | 41 | 4.964 | 81 | 1.113 | ||
| 2 | 31.12 | 42 | 4.763 | 82 | 1.076 | ||
| 3 | 29.528 | 43 | 4.571 | 83 | 1.041 | ||
| 4 | 28.026 | 44 | 4.387 | 84 | 1.007 | ||
| 5 | 26.608 | 45 | 4.213 | 85 | 0.974 | ||
| 6 | 25.268 | 46 | 4.046 | 86 | 0.942 | ||
| 7 | 24.003 | 47 | 3.887 | 87 | 0.912 | ||
| 8 | 22.808 | 48 | 3.735 | 88 | 0.883 | ||
| 9 | 21.678 | 49 | 3.59 | 89 | 0.855 | ||
| 10 | 20.61 | 50 | 3.451 | 90 | 0.828 | ||
| 11 | 19.601 | 51 | 3.318 | 91 | 0.802 | ||
| 12 | 18.646 | 52 | 3.191 | 92 | 0.777 | ||
| 13 | 17.743 | 53 | 3.069 | 93 | 0.753 | ||
| 14 | 16.888 | 54 | 2.952 | 94 | 0.73 |
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