MITSUBISHI ELECTRIC PEFY-P18NMAU-E3 (01) PDF DOCUMENT

The symbols used for the MITSUBISHI ELECTRIC PEFY-P18NMAU-E3 are explained as follows:

WARNING: This symbol indicates that failure to follow the instructions exactly as stated poses the risk of serious injury or death.

CAUTION: This symbol indicates that failure to follow the instructions exactly as stated poses the risk of serious injury or damage to the unit.

Circle with a diagonal line: Indicates an action that must be avoided.

Exclamation mark in a circle: Indicates important instructions.

Ground symbol: Indicates a part that requires grounding.

Fan symbol in a yellow triangle: Indicates that caution must be taken with rotating parts. (This symbol is on the main unit label.)

Lightning bolt in a yellow triangle: Indicates that the parts that are marked with this symbol pose a risk of electric shock. (This symbol is on the main unit label.)

When installing and servicing the MITSUBISHI ELECTRIC PEFY-P18NMAU-E3, adhere to the following WARNINGS:

• Do not use refrigerant other than the type indicated in the manuals and on the nameplate. Doing so may cause the unit or pipes to burst, or result in explosion or fire.

• Ask your dealer or a qualified technician to install the unit. Improper installation may result in water leakage, electric shock, or fire.

• Properly install the unit on a surface that can withstand its weight. An unstable surface may cause the unit to fall and cause injury.

• Only use specified cables. Securely connect each cable so that the terminals do not carry the weight of the cable. Improperly connected cables may produce heat and start a fire.

• Take appropriate safety measures against wind gusts and earthquakes to prevent the unit from toppling over.

• Only use accessories (e.g., air cleaners, humidifiers, electric heaters) recommended by Mitsubishi Electric.

• Do not make any modifications or alterations to the unit. Consult your dealer for repair, as improper repair may result in water leakage, electric shock, or fire.

• Do not touch the heat exchanger fins with bare hands as they are sharp and pose a risk of cuts.

• In the event of a refrigerant leak, thoroughly ventilate the room. Contact with an open flame will generate toxic gases.

• Properly install the unit according to the instructions in the Installation Manual to prevent water leakage, electric shock, or fire.

• Have all electrical work performed by an authorized electrician according to local regulations and the manual. Use a dedicated circuit.

• Keep electrical parts away from water, as wet parts pose a risk of electric shock, smoke, or fire.

• Securely attach the control box cover. If not installed properly, dust or water may infiltrate and cause electric shock, smoke, or fire.

• Only use the type of refrigerant indicated on the unit when installing or relocating. Infiltration of other refrigerants or air may cause pipes to burst or explode.

• When installing in a small space, take precautions to prevent leaked refrigerant from reaching the limiting concentration, which can cause oxygen starvation.

• Consult your dealer or a qualified technician when moving or reinstalling the unit.

• After completing service work, check for a refrigerant leak. If leaked refrigerant is exposed to a heat source, toxic gases will be generated.

• Do not try to defeat the safety features of the unit, such as pressure or temperature switches.

• Consult your dealer for proper disposal method.

• Do not use a leak detection additive.

When handling the MITSUBISHI ELECTRIC PEFY-P18NMAU-E3 with R410A refrigerant, observe the following CAUTIONS:

• Do not use existing refrigerant piping. Residual chlorine from old refrigerant and oil can cause the new unit’s refrigerator oil to deteriorate.

• Only use R410A. Other types of refrigerant containing chloride can cause the refrigerator oil to deteriorate.

• Use refrigerant piping made of phosphorus deoxidized copper. Keep pipe surfaces clean and free of contaminants like sulfur, oxides, dust, dirt, oil, and moisture.

• Use a vacuum pump with a check valve to prevent pump oil from flowing into the refrigerant cycle.

• Store piping materials indoors and keep both ends sealed until just before brazing to prevent contamination.

• Prepare tools for exclusive use with R410A. Do not use tools (gauge manifold, charging hose, leak detector, etc.) that have been used with conventional refrigerants.

• Use a small amount of ester oil, ether oil, or alkyl benzene to coat flares and flanges. Avoid large amounts of mineral oil.

• Do not use a charging cylinder, as it can alter the refrigerant composition.

• Charge the system with refrigerant in the liquid phase. If charged in the gaseous phase, the refrigerant composition in the cylinder will change and become unsuitable.

• Exercise special care when handling tools to prevent dust, dirt, or water from entering the refrigerant system.

Model	PEFY-P18NMAU-E3
Power source	1-phase 208/230V 60Hz
Cooling capacity (Nominal)	18,000 BTU/h / 5.3 kW
Cooling Power input	0.11 kW
Cooling Current input	0.77/0.73 A
Heating capacity (Nominal)	20,000 BTU/h / 5.9 kW
Heating Power input	0.09 kW
Heating Current input	0.66/0.62 A
External dimension H x W x D	9-7/8×35-7/16×28-7/8 in. / 250 x 900 x 732 mm
Net weight	58 lbs (26 kg)
FAN Type x Quantity	Sirocco fan x 1
External static press.	<0.14>-0.20-<0.28>-<0.40>-<0.60> in.WG
Motor type	DC motor
Motor output	0.085 kW
Airflow rate (Low-Mid-High)	424-512-600 cfm
Sound pressure level (Low-Mid-High)	28-32-35 dB <A>
Refrigerant control device	LEV
Connectable outdoor unit	R410A CITY MULTI
Diameter of refrigerant pipe (Liquid)	1/4 (6.35) Brazed in. (mm)
Diameter of refrigerant pipe (Gas)	1/2 (12.7) Brazed in. (mm)
Diameter of drain pipe	O.D. 1-1/4(32) in. (mm)

Component	Symbol	Specification
Room temperature thermistor	TH21	Resistance 0°C/15kΩ, 10°C/9.6kΩ, 20°C/6.3kΩ, 25°C/5.4kΩ, 30°C/4.3kΩ, 40°C/3.0kΩ
Liquid pipe thermistor	TH22	Resistance 0°C/15kΩ, 10°C/9.6kΩ, 20°C/6.3kΩ, 25°C/5.4kΩ, 30°C/4.3kΩ, 40°C/3.0kΩ
Gas pipe thermistor	TH23	Resistance 0°C/15kΩ, 10°C/9.6kΩ, 20°C/6.3kΩ, 25°C/5.4kΩ, 30°C/4.3kΩ, 40°C/3.0kΩ
Fuse	FUSE	250V 6.3A
Fan motor	–	8-pole, Output 85W SIC-70CW-D885-2
Linear expansion valve	LEV	12VDC Stepping motor drive port diameter ø3.2 (0-2000 pulse)
Power supply terminal block	TB2	(L1, L2, G) 250V 20A
Transmission terminal block	TB5, TB15	(1, 2) 250V 15A, (M1, M2, S) 250V 20A
Drain float switch	DS	Open/short detection. Initial contact resistance 500 mΩ or less

To operate the unit in Cool mode:

1. Press the POWER [ON/OFF] button.

2. Press the operation [Mode] button to display COOL.

3. Press the [Set Temperature] button to set the desired temperature. The set temperature changes by 2°F each time the button is pressed, within a range of 67°F to 87°F.

Control Functions in Cool Mode:

• Thermoregulating function: The unit has a 3-minute restart prevention function. Thermo ON occurs when the room temperature is ≥ desired temperature + 2°F. Thermo OFF occurs when the room temperature is ≤ desired temperature.

• Anti-freezing control: If the liquid pipe temperature (TH22) is 33.8°F or less for 16 minutes after the compressor starts, anti-freezing control starts and turns the thermo OFF. Control is cancelled when the liquid pipe temp rises to 50°F or above, or when the operation mode is changed or stopped.

• Fan: Fan speed can be set to [Low], [Med], [High], or [Auto]. In [Auto] mode, speed changes based on the difference between room temperature and desired temperature.

• Drain pump: The drain pump is always ON during COOL operation. When the mode is changed from COOL (or DRY) to another mode (including Stop), the drain pump runs for 3 more minutes before turning OFF.

• Float switch control: The float switch detects water if it remains ON for 15 seconds.

To operate the unit in Dry mode:

1. Press the POWER [ON/OFF] button.

2. Press the operation [Mode] button to display DRY.

3. Press the [Set Temperature] button to set the desired temperature. The set temperature changes by 2°F each time the button is pressed, within a range of 67°F to 87°F.

Thermo Regulating Function in Dry Mode:

The unit cycles on and off based on room temperature to control humidity. The ON/OFF cycle times vary as follows:

Room temperature	Thermo regulating signal	Room temperature (T1)	Dry thermo ON time (min)	Dry thermo OFF time (min)
Over 64°F	ON	T1 ≥ 83°F	9	3
		83°F > T1 ≥ 79°F	7	3
		79°F > T1 ≥ 75°F	5	3
		75°F > T1	3	3
Over 64°F	OFF	Unconditional	3	10
Less than 64°F	Dry thermo OFF

Fan Operation in Dry Mode:

• When Dry thermo is ON, the fan speed is [Low].

• When Dry thermo is OFF and the room temp is 64°F or higher, the fan speed is [Low].

• When Dry thermo is OFF and the room temp is below 64°F, the fan will Stop.

To operate the unit in Fan only mode:

1. Press the POWER [ON/OFF] button.

2. Press the operation [Mode] button to display FAN.

Fan Speed Control:

You can select from 3 speeds ([Low], [Med], [High]) or [Auto]. When [Auto] is set in Fan mode, the fan speed becomes [Low].

Drain Pump Control:

The drain pump will turn ON under the following conditions:

• For 3 minutes after the operation mode is switched from COOL or DRY to FAN mode.

• For 6 minutes if the float switch detects water.

To operate the unit in Heat mode:

1. Press the POWER [ON/OFF] button.

2. Press the operation [Mode] button to display HEAT.

3. Press the [Set Temperature] button to set the desired temperature. The set temperature changes by 2°F each time the button is pressed, within a range of 63°F to 83°F.

Displays in HEAT operation:

• [DEFROST]: Displayed during the defrost operation.

• [STANDBY]: Displayed during the hot adjust mode.

Control Functions in Heat Mode:

• Thermoregulating function: The unit has a 3-minute restart prevention function. Thermo ON occurs when room temperature ≤ desired temperature – 2°F. Thermo OFF occurs when room temperature ≥ desired temperature.

• Fan: Fan speed can be set to [Low], [Med], [High], or [Auto]. Fan operation gives priority to the following control modes: Hot adjust, Preheating exclusion, Thermo OFF (cool air prevention), Defrosting, and Capacity increasing.

• Hot adjust mode: At the start of HEAT operation, the fan runs at [Extra Low] or [Low] to prevent cold drafts. “STAND BY” is displayed during this mode. The unit returns to the set fan speed after 2 minutes, or after 5 minutes if the indoor liquid pipe temperature reaches 95°F or more.

• Heat defrosting mode: The indoor fan stops during defrost.

To use Auto operation mode:

1. Press POWER [ON/OFF] button.

2. Press the operation [Mode] button to display AUTO.

3. Press the [Set Temperature] button to set the desired temperature, from 67°F to 83°F.

How Auto Mode Works:

• Initial Operation: If the room temperature is less than the desired temperature, the unit starts in HEAT mode. If the room temperature is greater than or equal to the desired temperature, it starts in COOL mode.

• Mode Change:

– HEAT to COOL: The unit switches to COOL mode when the room temperature is greater than the desired temperature + 3°F for 3 minutes.

– COOL to HEAT: The unit switches to HEAT mode when the room temperature is less than or equal to the desired temperature – 3°F for 3 minutes.

• Operation in COOL/HEAT: Once a mode is selected, the unit operates with the same controls as the standard COOL or HEAT mode.

To check the Room temperature thermistor (TH21), Liquid pipe thermistor (TH22), or Gas pipe thermistor (TH23):

1. Disconnect the thermistor’s connector from the control board.

2. Measure the resistance between its terminals with a tester.

3. Compare the reading to the expected values. At an ambient temperature of 50°F – 86°F (10°C – 30°C), the normal resistance should be between 9.6kΩ and 4.3kΩ.

• If the resistance is within this range, it is Normal.

• If the reading is open or short, the thermistor is Abnormal and should be replaced.

Thermistor Resistance Values at Various Temperatures:

• 32°F (0°C): 15kΩ

• 50°F (10°C): 9.6kΩ

• 68°F (20°C): 6.3kΩ

• 77°F (25°C): 5.2kΩ

• 86°F (30°C): 4.3kΩ

• 104°F (40°C): 3.0kΩ

To test the linear expansion valve (LEV):

1. Disconnect the LEV connector (CN60) from the control board.

2. Measure the resistance between the terminals of the LEV motor coils.

The normal resistance across each coil is 200Ω ±10%.

• Terminals 1-5 (White-Red)

• Terminals 2-6 (Yellow-Brown)

• Terminals 3-5 (Orange-Red)

• Terminals 4-6 (Blue-Brown)

If any coil is open or short, the LEV is abnormal and should be replaced.

The LEV is a stepping motor that operates based on pulse signals from the indoor control board. When the valve position changes, the output pulse changes in the order 1 -> 2 -> 3 -> 4 -> 1 to close, and 4 -> 3 -> 2 -> 1 -> 4 to open. If any signal is missing or stays ON, the motor will vibrate and make a clicking noise.

Symptom	Checking Criteria	Remedy
Circuit failure on the microcomputer	Disconnect the connectors on the control board and connect LEDs to the driving circuit. Pulse signals are output for 10 seconds when the main power is turned on. If there are LEDs that do not light up or remain lit after the pulses are turned off, there is a problem with the driving circuit.	Replace the indoor control board if driving circuit failure is detected.
Locked LEV	The motor will idle and make a small clicking noise if run while locked. If this noise is heard both when the valve is fully closed and when opening, it indicates a problem.	Replace the LEV.
Disconnected or shorted LEV motor coils	Measure the resistance between the coils (red-white, red-orange, brown-yellow, brown-blue). The normal range is 200 Ω±10%.	Replace the LEV.
Valve closure failure (leaky valve)	To check the LEV, check the indoor unit liquid pipe temperature (TH22) on the outdoor unit’s operation monitor. Operate the indoor unit in FAN mode while other units are in COOL mode. Normally, the LEV is fully closed. If the valve is leaky, the TH22 reading will be lower than normal (cooler than the room inlet air temperature).	Replace the LEV if the amount of leakage is significant.

Drain-up mechanism (Drain Pump):

Measure the resistance between terminals 1 and 3 of the drain pump connector. At a coil temperature of 68°F (20°C), the normal resistance is 340 Ω. An open or short reading indicates an abnormal pump.

Drain float switch (CN4F):

1. Disconnect the float switch connector from the control board.

2. Measure the resistance between the terminals while manually moving the float.

Position of the moving part	Normal Reading	Abnormal Reading
Up (water detected)	Short (continuity)	Any position but short
Down (no water)	Open (no continuity)	Any position but open

CAUTION: A high voltage is applied to the fan motor connector (CNMF). Do not unplug it while the unit is energized.

If the indoor unit fan does not run, follow these steps:

1. Check Connection: Ensure the fan motor connector (CNMF) is fully inserted. If not, fix the connection.

2. Check Power Supply Voltage: Measure the DC voltage at the indoor control board between fan connector pins 1 (+) and 4 (-). The voltage should correspond to the AC input voltage:

• 208VAC -> 294VDC

• 220VAC -> 311VDC

• 230VAC -> 325VDC

• 240VAC -> 340VDC

Also, check Vcc (pin 5 to 4), which should be 15VDC, and Vsp (pin 6 to 4), which should be 1-6.5VDC when running (0V when stopped). If the voltage is not within the normal range, replace the indoor control board.

3. Check Position Signal: If voltages are normal, check the fan motor position thermistor signal (VFG). Measure the voltage between fan connector pins 7 (+) and 4 (-). As the motor rotates, the voltage should alternate between 0VDC and 15VDC.

• If the voltage does not alternate, replace the motor.

• If the voltage alternates correctly, replace the indoor control board.

Important: Make sure power to the unit is turned off before setting the address.

On-site address setting is required for the indoor units to run when using an ME remote controller. Address setting is not required when using the unit remote controller.

1. Locate the rotary switches SW11 (1’s digit) and SW12 (10’s digit) on the indoor unit control board.

2. Set the address by combining the settings of SW12 and SW11.

• To set the address to “3”, set SW12 to “0” and SW11 to “3”.

• To set the address to “25”, set SW12 to “2” and SW11 to “5”.

Address settings vary in different systems. Refer to the section on address setting in the outdoor unit installation manual for system-specific requirements.

Exercise caution when removing heavy parts.

To remove the control box cover:

1. Remove the three fixing screws on the cover.

2. Lift the cover off the unit.

When reinstalling, tighten the screws to a torque of 2.0±0.2 N.m.

Exercise caution when removing heavy parts.

1. Remove the control box cover as described in the previous procedure.

2. Locate the thermistor holder on the control box.

3. Pull out the thermistor holder and the thermistor from the control box.

Exercise caution when removing heavy parts. Note: Drain the water out of the drain pan before removing it.

1. Remove the filter and bottom plate:

a. Push down the tab on the filter and pull the filter out.

b. Remove the fixing screws on the bottom plate to remove it. When reinstalling, tighten these screws to a torque of 1.4±0.2 N.m.

2. Remove the drain pan:

a. Pull out the drain pan in the direction indicated by the arrow in the manual.

Exercise caution when removing heavy parts.

1. Remove the drain pan according to the procedure for drain pan removal.

2. Remove the heat exchanger cover:

a. Remove the four fixing screws on the heat exchanger cover to remove it. When reinstalling, tighten these screws to a torque of 1.4±0.2 N.m.

3. Remove the thermistor:

a. Remove the thermistor from the thermistor holder on the copper tube.

Exercise caution when removing heavy parts.

1. Remove the filter and bottom plate:

a. Push down the tab on the filter and pull it out.

b. Remove the fixing screws on the bottom plate to remove it. Tighten screws to a torque of 1.4±0.2 N.m upon reassembly.

2. Remove the fan casing (bottom half):

a. Squeeze the tabs on the fan casing to release it and remove it.

3. Remove the motor cable:

a. Remove the motor cable through the rubber bush.

4. Remove the fan motor and Sirocco fan:

a. Remove the two motor fixing screws to remove the motor and the Sirocco fan assembly. Tighten screws to a torque of 3.5±0.2 N.m upon reassembly.

b. Remove the four fan case fixing screws to take the top half of the fan casing off. Tighten screws to a torque of 1.4±0.2 N.m upon reassembly.

Exercise caution when removing heavy parts.

1. Remove the drain pan.

2. Remove the heat exchanger cover.

3. Remove the pipe support plate:

a. Remove the five fixing screws on the cover (pipe support plate) to remove it. Tighten these screws to a torque of 2.0±0.2 N.m when reinstalling.

4. Remove the heat exchanger:

a. Remove the fixing screws on the heat exchanger to remove it. Tighten these screws to a torque of 1.4±0.2 N.m when reinstalling.