MITSUBISHI ELECTRIC PEFY-P24NMAU-E3 (01) PDF DOCUMENT

Always observe the following safety precautions for your safety when installing and operating the MITSUBISHI ELECTRIC PEFY-P24NMAU-E3:

WARNING

• 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 an 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.

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

• In the event of a refrigerant leak, thoroughly ventilate the room. Toxic gases will be generated if gaseous refrigerant comes into contact with an open flame.

• 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 instructions. 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 to prevent dust or water from infiltrating.

• Only use the type of refrigerant indicated on the unit when installing or relocating. Infiltration of other refrigerants or air may adversely affect the refrigerant cycle.

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

• After completing service work, check for a refrigerant leak.

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

• Do not use a leak detection additive.

CAUTION

• Do not use the existing refrigerant piping, as residual chlorine may cause the new unit’s refrigerator oil to deteriorate.

• Use refrigerant piping materials made of phosphorus deoxidized copper. Keep pipe surfaces clean and free of contaminants.

• Store piping materials indoors with both ends sealed until brazing.

• Use a small amount of ester oil, ether oil, or alkyl benzene to coat flares and flanges. Infiltration of a large amount of mineral oil may cause the refrigerator oil to deteriorate.

• Charge the system with refrigerant in its liquid phase.

• Only use R410A. The use of other refrigerants may cause refrigerator oil deterioration.

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

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

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

• Exercise special care when handling tools for use with R410A to prevent infiltration of dust, dirt, or water.

1	[Set Temperature] Button	7	[Vane Control] Button
2	[Timer Menu] Button / [Monitor/Set] Button	8	[Ventilation] Button / [Operation] Button
3	[Mode] Button / [Back] Button	9	[Check/Clear] Button
4	[Timer On/Off] Button / [Set Day] Button	10	[Test Run] Button
5	[Louver] Button / [Operation] Button	11	[Filter] Button / [ ] Button
6	[Fan Speed] Button	12	[ON/OFF] Button
		13	Position of built-in room thermistor
		14	[Set Time] Button

Keep the remote controller out of direct sunlight to ensure accurate measurement of room temperature. The thermistor at the lower right-hand section of the remote controller must be free from obstructions to ensure accurate measurement of room temperature.

To operate 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 temperature changes by 2°F per press, with a range of 67°F to 87°F.

Thermoregulating Function:

• Thermo ON: Room temperature is greater than or equal to the desired temperature + 2°F.

• Thermo OFF: Room temperature is less than or equal to the desired temperature.

Anti-freezing Control:

If the liquid pipe temperature (TH22) is 33.8°F or less within 16 minutes of compressor start-up, anti-freezing control starts, and the unit turns off (thermo OFF). Control is cancelled when the liquid pipe temperature rises to 50°F or above, or when the operation stops or changes mode.

Fan Operation:

You can select from 3 speeds ([Low], [Med], [High]) plus an [Auto] setting. In [Auto] mode, the fan speed changes based on the difference between the room temperature and the set temperature.

Drain Pump Control:

The drain pump is always ON during COOL and DRY mode operation. When the mode is changed from COOL or DRY, the drain pump continues to run for 3 minutes before turning OFF. If the float switch detects water for 15 seconds, it will signal an abnormal condition.

To operate in Dry mode:

1. Press 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 temperature changes by 2°F per press, with a range of 67°F to 87°F.

Thermoregulating Function:

The unit cycles on and off based on the room temperature to dehumidify the air. The ON/OFF cycle times vary as shown in the table below:

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
	OFF	Unconditional	3	10
Less than 64°F	Dry thermo OFF

Fan Operation:

The indoor fan operation depends on the compressor conditions. It operates at [Low] speed when the dry thermo is ON. It stops when the dry thermo is OFF, unless the room temperature is below 64°F, in which case it continues at [Low].

To operate in Fan mode:

1. Press POWER [ON/OFF] button.

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

Fan Speed:

You can select from 3 speeds ([Low], [Med], [High]) plus an [Auto] setting. When [Auto] is set, the fan speed defaults to [Low].

Drain Pump Control:

The drain pump will run for a specified amount of time under these conditions:

• For 3 minutes after switching from COOL or DRY mode to FAN mode.

• For 6 minutes after the float switch detects water.

To operate in Heat mode:

1. Press 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 temperature changes by 2°F per press, with a range of 63°F to 83°F.

The remote controller will display [DEFROST] during the defrost operation and [STANDBY] during the hot adjust mode.

Thermoregulating Function:

• Thermo ON: Room temperature is less than or equal to the desired temperature – 2°F.

• Thermo OFF: Room temperature is greater than or equal to the desired temperature.

Fan Operation:

• You can select from 3 speeds ([Low], [Med], [High]) plus an [Auto] setting. In [Auto] mode, fan speed is adjusted based on the difference between the desired and room temperatures.

• Hot Adjust Mode: At the start of HEAT operation, the fan runs at [Extra Low] or [Low] to prevent cold drafts. The remote controller will show “STAND BY”.

• Thermo OFF Mode: When the room reaches the set temperature, the fan operates at [Extra low].

• Heat Defrosting Mode: The indoor fan stops during defrosting.

To use Auto operation:

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. The temperature changes by 2°F per press, with a range of 67°F to 83°F.

Mode Selection:

• The unit starts in HEAT mode if the room temperature is less than the desired temperature.

• The unit starts in COOL mode if the room temperature is greater than or equal to the desired temperature.

Mode Change:

• HEAT to COOL: The unit will switch if the room temperature exceeds the desired temperature by +3°F for 3 minutes.

• COOL to HEAT: The unit will switch if the room temperature is at or below the desired temperature by -3°F for 3 minutes.

Thermistors (TH21, TH22, TH23) Check:

Disconnect the connector and measure the resistance. At an ambient temperature of 50°F-86°F (10°C-30°C), the normal resistance should be between 4.3 kΩ and 9.6 kΩ. If it’s open or shorted, it’s abnormal.

Linear Expansion Valve (LEV) Check:

Disconnect the connector and measure the resistance between terminals with a tester. The normal resistance between terminal pairs 1-5, 2-6, 3-5, and 4-6 is approximately 200 kΩ ±10%.

Drain-up Mechanism Check:

Measure the resistance between terminals 1 and 3. Normal resistance is approximately 340 Ω at 68°F (20°C). An open or short circuit is abnormal.

Drain Float Switch (CN4F) Check:

Disconnect the connector and test for continuity. When the moving part is UP, it should be shorted. When it is DOWN, it should be open. Any other result indicates an abnormality.

Follow these troubleshooting steps:

1. Check Connector: Ensure the fan motor connector (CNMF) is fully inserted into the indoor control board.

2. Check Power Supply: Measure the voltage at the indoor control board. It should be between 294-340VDC (between fan connector 1 (+) and 4 (-)). Check the voltage between fan connector 5 (+) and 4 (-) which should be 15VDC. Also, check the voltage between fan connector 6 (+) and 4 (-) which should be 1-6.5VDC while the motor is running (0V when stopped). If the voltages are not within the normal range, replace the indoor control board.

3. Check Motor Signal: Get the motor to make a full rotation or more and measure the voltage at the test point VFG (between fan connector 7 (+) and 4 (-)). It should alternate between 0VDC and 15VDC.

• If 0VDC and 15VDC are displayed alternately, the motor is likely faulty. Replace the indoor control board.

• If the voltage does not alternate as expected, the motor is faulty. Replace the motor.

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

Make sure the power to the unit is turned off before setting the address. On-site address setting is required for the indoor units to run.

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

• The address is set by combining the values of the two switches. For example:

• 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 setting is required when using an ME remote controller. It is not required when using a unit-specific remote controller.

Dipswitch settings must be made while the unit is stopped. Changes to SW1, SW2, and SW3 become effective when the unit comes to a stop (remote controller OFF). Power cycling is not required for these switches. SW5 must be set with the main power turned OFF.

SW1 – Function Setting

Switch	Function	ON	OFF (Factory Setting)
1	Active Thermistor	Built-in thermistor on remote controller	Indoor unit
2	Filter clogging detection	Available	Unavailable
3	Filter life	2500 hr	100 hr
4	Outdoor air intake	Enabled	Disabled
5	Remote display	Thermo-ON signal	Fan output
6	Humidifier operation	During heating mode	During heating operation
7	Fan speed	Low	Very low
8	Fan speed at heating Thermo-OFF	Preset fan speed	Follows the setting of SW1-7
9	Auto restart after power failure	Enabled	Disabled
10	Power start/stop	Enabled	Disabled

SW3 – Unit Type Setting

SW3-1 determines the unit type: ON for Cooling only, OFF for Heat pump (factory setting).

SW5 – Power Voltage Setting

Set SW5 to the 240V side for a 230V power supply (factory setting). Set it to the 220V side for a 208V power supply.

SWA, SWC – External Static Pressure

These switches set the external static pressure. The factory setting is 50Pa (0.20in.WG). Changes are effective immediately.

Exercise caution when removing heavy parts. Always disconnect power before servicing.

1. Control Box

• Remove the three fixing screws on the control box cover to remove it.

2. Thermistor (Intake Air)

• After removing the control box cover, pull out the thermistor holder and thermistor from the control box.

3. Drainpan

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

• Remove the fixing screws on the bottom plate to remove it.

• Drain any water from the drain pan, then pull the drain pan out to remove it.

4. Thermistor (Gas/Liquid Pipe)

• Remove the drain pan first.

• Remove the four fixing screws on the heat exchanger cover to remove it.

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

5. Fan and Fan Motor

• Remove the filter and bottom plate.

• Squeeze the tabs on the bottom half of the fan casing to remove it.

• Remove the motor cable from the rubber bush.

• Remove the two motor fixing screws to remove the motor and Sirocco fan assembly.

• Remove the four fan case fixing screws to separate the top half of the fan casing.

6. Heat Exchanger

• Remove the drain pan and heat exchanger cover.

• Remove the five fixing screws on the pipe support plate to remove it.

• Remove the fixing screws on the heat exchanger to remove it.