MITSUBISHI ELECTRIC PEFY-P48NMAU-E3 (01) PDF DOCUMENT

Always read and follow these safety precautions for your safety.

WARNING

Do not use refrigerant other than the type indicated in the manuals and on the nameplate (R410A). 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. The fins are sharp and pose a risk of cuts.

In the event of a refrigerant leak, thoroughly ventilate the room. If gaseous refrigerant leaks and contacts an open flame, toxic gases will be generated.

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 instructions in this manual. Use a dedicated circuit.

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

Securely attach the control box cover to prevent dust or water from infiltrating, which could pose a risk of electric shock, smoke, or fire.

When installing the unit in a small space, take appropriate 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.

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.

CAUTION

Do not use the existing refrigerant piping. Residual chlorine may cause the refrigerator oil in the new unit to deteriorate.

Use refrigerant piping materials made of phosphorus deoxidized copper. Keep the inner and outer surfaces of the pipes clean and free of contaminants.

Store piping materials indoors and keep 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 can cause refrigerator oil to deteriorate.

Charge the system with refrigerant in the liquid phase. If gaseous refrigerant is drawn out first, the composition will change and become unsuitable for use.

Only use R410A. Other refrigerants containing chloride may cause the refrigerator oil to deteriorate.

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

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

Do not use a charging cylinder, as the refrigerant composition in the cylinder will change and become unsuitable for use.

Exercise special care when handling tools to prevent infiltration of dust, dirt, or water into the refrigerant system.

The buttons on the remote controller have the following functions:

1. [Set Temperature] Button

2. [Timer Menu] Button / [Monitor/Set] Button

3. [Mode] Button / [Back] Button

4. [Timer On/Off] Button / [Set Day] Button

5. [Louver] Button / [Operation] Button

6. [Fan Speed] Button

7. [Vane Control] Button

8. [Ventilation] Button / [Operation] Button

9. [Check/Clear] Button

10. [Test Run] Button

11. [Filter] Button / [▶] Button

12. [ON/OFF] Button

13. Position of built-in room thermistor

14. [Set Time] Button

Note: Keep the remote controller out of direct sunlight and ensure the thermistor at the lower right-hand section is free from obstructions for accurate room temperature measurement.

The display indicators have the following meanings:

A. Current time/Timer time

B. Centralized control indicator

C. Timer OFF indicator

D. Timer mode indicator

E. Operation mode display: COOL, DRY, AUTO, FAN, HEAT

F. Function mode indicator

G. Preset temperature

H. Power indicator

I. Louver swing

J. Ventilation

K. Filter sign

L. Sensor position

M. Room temperature

N. Vane setting

O. Fan speed

P. Operation lamp

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 temperature changes by 2°F each time the button is pressed, within a range of 67°F to 87°F.

Mode Details:

Thermoregulating function: The compressor turns on (Thermo ON) when the room temperature is greater than or equal to the desired temperature + 2°F. It turns off (Thermo OFF) when the room temperature is less than or equal to the desired temperature. There is a 3-minute restart prevention function.

Anti-freezing control: If the liquid pipe temperature (TH22) drops to 33.8°F or less within 16 minutes of the compressor starting, anti-freezing control starts and the compressor turns off. Control is cancelled when the liquid pipe temperature rises to 50°F or above, or after other conditions are met.

Fan: You can select from [Low], [Med], [High], and [Auto] fan speeds. In Auto mode, the fan speed changes based on the difference between the room temperature and the desired temperature.

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 temperature changes by 2°F each time the button is pressed, within a range of 67°F to 87°F.

Mode Details:

Thermoregulating function: The unit cycles the compressor on and off based on room temperature to dehumidify the air. The ON/OFF cycle times vary with room temperature 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
Less than 64°F	OFF	Unconditional	3	10
	Dry thermo OFF

Fan: The fan operates at [Low] speed when the compressor is on. When the compressor is off, the fan will stop, except when the room temperature is below 64°F, in which case it will continue at [Low] speed.

To operate the unit in Fan only mode:

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

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

Mode Details:

Fan: You can select from [Low], [Med], [High], and [Auto] fan speeds. When [Auto] is set, the fan speed becomes [Low].

Drain pump: The drain pump will run for 3 minutes if the mode is switched from COOL or DRY to FAN. It will also run 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 temperature changes by 2°F each time the button is pressed, within a range of 63°F to 83°F.

Mode Details:

Display: [DEFROST] is displayed during the defrost operation. [STANDBY] is displayed during the hot adjust mode.

Thermoregulating function: The compressor turns on (Thermo ON) when the room temperature is less than or equal to the desired temperature – 2°F. It turns off (Thermo OFF) when the room temperature is greater than or equal to the desired temperature. There is a 3-minute restart prevention function.

Fan Control:

You can select from [Low], [Med], [High], and [Auto] fan speeds. The fan speed is also influenced by several control modes:

Hot adjust mode: At the start of HEAT operation, the fan runs at [Extra Low] or [Low] for a few minutes to prevent cold drafts. “STAND BY” is displayed during this time.

Preheating exclusion mode: When an auxiliary heater turns off, the indoor fan operates in [Low] mode for 1 minute.

Thermo OFF mode: When the room reaches the set temperature and the compressor turns off, the indoor fan operates in [Extra low].

Heat defrosting mode: The indoor fan stops during the outdoor unit’s defrost cycle.

To operate the unit in Automatic mode:

1. Press the 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 each time the button is pressed, within a range of 67°F to 83°F.

Mode Details:

Initial mode: The unit starts in HEAT mode if the room temperature is less than the desired temperature, and in COOL mode if it is greater than or equal to the desired temperature.

Mode change:

The unit will switch from HEAT to COOL mode if the room temperature exceeds the desired temperature by 3°F (or after 3 minutes).

The unit will switch from COOL to HEAT mode if the room temperature is less than or equal to the desired temperature – 3°F (or after 3 minutes).

The control within COOL or HEAT mode is the same as the standard operation for those modes.

Drain Pump Control:

The drain pump always runs during COOL and DRY mode operation.

When the operation mode is changed from COOL or DRY to another mode (including Stop), the drain pump continues to run for 3 minutes to clear any remaining water.

In other modes like FAN or HEAT, the drain pump turns on for a specified time under certain conditions, such as after switching from COOL/DRY mode or when the float switch detects water.

Float Switch Control:

The system checks if the float switch sensor is in water or air.

If the float switch is ON (in water) for 15 consecutive seconds, it is detected as being in water.

If the float switch is OFF (in air) for 15 consecutive seconds, it is detected as being in air.

If water is detected, the drain pump will run for 6 minutes.

If the float switch continuously detects water and air in a cycle, this can lead to an error postponement and eventually a “Drain pump abnormal” error.

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

1. Disconnect the connector for the thermistor you want to test.

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

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

A reading of open or short indicates an abnormal thermistor that needs to be replaced.

Reference resistance values at different temperatures:

0°C (32°F): 15 kΩ

10°C (50°F): 9.6 kΩ

20°C (68°F): 6.3 kΩ

25°C (77°F): 5.2 kΩ

30°C (86°F): 4.3 kΩ

40°C (104°F): 3.0 kΩ

The LEV is a stepping motor that controls refrigerant flow. When troubleshooting the LEV, follow these steps:

Symptom	Checking Criteria	Remedy
Circuit failure on the microcomputer	Disconnect the connectors on the control board and connect LEDs to test the 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 a driving circuit failure is detected.
Locked LEV	The motor will idle and make a small clicking noise if it is run while the LEV is locked. Listen for this noise with a screwdriver. If clicking is heard when the valve should be fully closed and while opening, it indicates a problem.	Replace the LEV.
Disconnected or shorted LEV motor coils	Measure the resistance between the coils with a tester (red-white, red-orange, brown-yellow, brown-blue). The normal range of resistance is 200 Ω ±10%.	Replace the LEV.
Valve closure failure (leaky valve)	Check the indoor unit liquid pipe temperature on the outdoor unit’s monitor while the indoor unit is in FAN mode and other units are in cooling mode. Normally, the LEV is fully closed. If the liquid pipe temperature is significantly lower than the room air temperature, a leaky valve is suspected.	Replace the LEV if the amount of leakage is great.

If the indoor unit fan does not run, follow this troubleshooting procedure. CAUTION: A high voltage is applied to the fan motor connector (CNMF). Do not unplug it while the unit is energized.

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

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

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 the fan is running (0V when stopped). If the voltages are not within the normal range, replace the indoor control board.

3. Check Position Signal (VFG): If voltages are normal, check the fan motor position signal. Get the motor to make a full rotation or more and measure the voltage at the test point VFG (between fan connector pins 7 (+) and 4 (-)).

4. Analyze VFG Signal: Does the voltage alternate between 0VDC and 15VDC? If yes, the motor is sending a signal but the board is not processing it, so replace the indoor control board. If no, the motor is not sending the signal, so replace the motor.

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.

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

2. Refer to the outdoor unit installation manual for the correct address settings for your specific system.

3. Set the address by combining the settings of SW12 and SW11. 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.”

Dipswitch settings must be made while the unit is stopped. SW1 controls the following functions:

Switch position	Function	ON	OFF (Factory Setting)
1	Active Thermistor (Intake air thermistor)	Built-in thermistor on the 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

The external static pressure is set using dipswitches SWA and SWC on the indoor control board. Changes made to these switches become effective immediately, regardless of the unit’s operation status.

External Static Pressure	SWA Setting	SWC Setting
35Pa (0.14in.WG)	1: OFF, 2: OFF	1: ON, 2: OFF
50Pa (0.20in.WG) (Factory Setting)	1: ON, 2: OFF	1: ON, 2: OFF
70Pa (0.28in.WG)	1: OFF, 2: ON	1: ON, 2: OFF
100Pa (0.40in.WG)	1: ON, 2: ON	1: ON, 2: OFF
150Pa (0.60in.WG)	1: ON, 2: ON	1: OFF, 2: ON

Exercise caution when removing heavy parts.

1. To remove the control box cover, locate and 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 its removal procedure.

2. Locate the thermistor holder and the thermistor on the control box.

3. Pull out the thermistor holder and the thermistor to remove them.

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

1. Remove Filter and Bottom Plate:

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

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 Drainpan:

Pull out the drain pan in the direction indicated by the arrow in the manual’s diagram.

Exercise caution when removing heavy parts.

1. Remove Filter and Bottom Plate: First, remove the air filter and the bottom plate by removing its fixing screws. (Reinstallation torque: 1.4±0.2 N.m).

2. Remove Fan Casing (Bottom Half): Squeeze the tabs on the fan casing and pull to remove the bottom half.

3. Remove Motor Cable: Pull the motor cable through the rubber bush.

4. Remove Fan Motor and Sirocco Fan:

Remove the two motor fixing screws to release the motor and the Sirocco fan assembly. (Reinstallation torque: 3.5±0.2 N.m).

5. Separate Fan Casing (Top Half): Remove the four fan case fixing screws to take the top half of the fan casing off. (Reinstallation torque: 1.4±0.2 N.m).

Exercise caution when removing heavy parts.

1. Remove the drain pan following its specific removal procedure.

2. Remove the heat exchanger cover by removing the five fixing screws on the cover (K), which acts as a pipe support plate. (Reinstallation torque: 2.0±0.2 N.m).

3. Remove the fixing screws on the heat exchanger (M) to remove it from the unit. (Reinstallation torque: 1.4±0.2 N.m).