Mitsubishi Electric PUMY-P125YHMB User Manual (English)

Questions and Answers:

L
Laurie AcostaAug 16, 2025
What to do if discharge/compressor temperature thermistor (TH4) exceeds limits in Mitsubishi Electric PUMY-P125YHMB Air Conditioner?
- D
  Dan MccannAug 16, 2025
  If the discharge/compressor temperature thermistor (TH4) exceeds 125 or 110 continuously for 5 minutes in your Mitsubishi Electric Air Conditioner, it indicates a problem. This could be due to an over-heated compressor caused by a shortage of refrigerant, defective operation of the stop valve, a defective thermistor, a defective outdoor controller board, or a defective linear expansion valve. To address this, check the intake super heat, look for refrigerant leakage and add more refrigerant if needed. Make sure the stop valve is fully open. Turn the power off, then on again, and check if error code 5101 is displayed. If it is, refer to the 'Check points' for 5101. Also, check the linear expansion valve.
E
Elizabeth JacksonAug 20, 2025
What to do if 63L operates under -0.03MPa during compressor operation in Mitsubishi Electric Air Conditioner?
- A
  Aaron MirandaAug 20, 2025
  If 63L operates below -0.03MPa during compressor operation of your Mitsubishi Electric Air Conditioner, it could be due to several reasons. The stop valve of the outdoor unit might be closed, there could be a disconnection or loose connection of connector (63L) on the outdoor controller board or of 63L itself, a defective outdoor controller board, refrigerant leakage or shortage, or a malfunction of the linear expansion valve. To fix this, check the stop valve and the connector (63L) on the outdoor controller board. Correct the refrigerant amount to the proper level and inspect the linear expansion valve.
M
Michael MunozAug 25, 2025
What to do if detecting mode conditions are satisfied during compressor operation in Mitsubishi Electric PUMY-P125YHMB?
- C
  christopher09Aug 25, 2025
  If your Mitsubishi Electric Air Conditioner is in HEAT mode and meets specific conditions, including a discharge super heat of 80 or more, a temperature difference (TH7-TH3) less than 5, and a high-pressure sensor reading below 2.04MPa, it may indicate a problem. This could be due to gas leakage or shortage, especially during heating operation, or a ball valve performance failure. To resolve this, check the refrigerant amount and the operation condition. Also, verify that the ball valve is fully opened.
K
kharrisAug 27, 2025
How to troubleshoot malfunction of drain pump in Mitsubishi Electric Air Conditioner?
- L
  lawsontheresaAug 27, 2025
  A malfunctioning drain pump in your Mitsubishi Electric Air Conditioner could be caused by several factors: a defective drain, a clogged drain pump or pipe, water drops on the drain sensor (possibly from lead wire trickling or a clogged filter causing drain wave), or a defective indoor controller board. To troubleshoot, first, check if the drain pump is working. Then, inspect the drain function. Check the lead wire setting of the drain sensor and inspect the filter for clogs. If none of these issues are present, consider replacing the indoor controller board.
D
Danielle LangSep 1, 2025
What to do if drain sensor detects water and temperature difference in Mitsubishi Electric PUMY-P125YHMB?
- K
  Kristine PerezSep 1, 2025
  If the drain sensor in your Mitsubishi Electric Air Conditioner detects being soaked in water 10 times in a row, and the liquid pipe temperature minus room temperature is -10deg[-18°F] for 30 minutes, it indicates a malfunction of the drain pump. Check if the drain pump is working and inspect the drain function.
P
Pamela LeeSep 4, 2025
Why outdoor fan motor rotational frequency is abnormal in Mitsubishi Electric PUMY-P125YHMB Air Conditioner?
- K
  Kristin LaraSep 4, 2025
  If the rotational frequency of the fan motor is abnormal during operation in your Mitsubishi Electric Air Conditioner, it suggests an issue with the outdoor fan motor. This could be due to failure in the operation of the DC fan motor or failure in the outdoor circuit controller board. To address this, check or replace the DC fan motor. Also, check the voltage of the outdoor circuit controller board during operation and replace the board if necessary.
M
maryfullerSep 8, 2025
What to do if float switch detects water and turns on and off abnormally in Mitsubishi Electric PUMY-P125YHMB Air Conditioner?
- Q
  qhardySep 8, 2025
  If the float switch in your Mitsubishi Electric Air Conditioner detects water and turns on and off abnormally, it indicates a defective moving part of the float switch. Check the moving part of the float switch.

Mitsubishi Electric PUMY-P125YHMB Specifications

General

Brand	Mitsubishi Electric
Model	PUMY-P125YHMB
Category	Air Conditioner
Language	English

Summary

1 TECHNICAL CHANGE

2 SAFETY PRECAUTION

2-1. CAUTIONS RELATED TO NEW REFRIGERANT

Cautions for units utilizing refrigerant R410A.

2-2. PRECAUTIONS FOR SALT PROOF TYPE "-BS" MODEL

Precautions to maintain the performance of the "-BS" model.

3 UNIT OVERVIEW

3-1. UNIT CONSTRUCTION

Details on the construction and connection of outdoor and indoor units.

3-2. UNIT SPECIFICATIONS

Details specifications for outdoor units and model identification.

4 SPECIFICATIONS

5 DATA

5-1. COOLING AND HEATING CAPACITY AND CHARACTERISTICS

Methods for calculating system cooling/heating capacity and characteristics.

5-2. STANDARD CAPACITY DIAGRAM

Diagrams showing standard capacity based on total indoor unit capacity.

6 OUTLINES AND DIMENSIONS

Piping Knockout Hole Details

Details on the location and size of piping and wiring knockouts.

7 WIRING DIAGRAM

Cautions when Servicing

Important warnings and notes for servicing wiring diagrams.

Self-diagnosis function

Explanation of the self-diagnosis function using switches and LEDs.

8 NECESSARY CONDITIONS FOR SYSTEM CONSTRUCTION

8-1. TRANSMISSION SYSTEM SETUP

Guidelines for setting up the transmission system and addresses.

8-2. REFRIGERANT SYSTEM DIAGRAM

Diagrams illustrating the refrigerant flow and components.

8-3. SYSTEM CONTROL

Information on system control and remote controller operations.

9 TROUBLESHOOTING

9-1. CHECK POINTS FOR TEST RUN

Procedure for verifying system operation after installation.

9-1-2. Special Function Operation and Settings (for M-NET Remote Controller)

Details on group and paired settings for M-NET remote controllers.

9-1-3. Countermeasures for Error During Test Run

Troubleshooting steps for error codes encountered during test runs.

9-5. INTERNAL SWITCH FUNCTION TABLE

9-6. OUTDOOR UNIT INPUT/OUTPUT CONNECTOR

State (CN51)

Details the connections and functions of the CN51 connector.

Auto change over (CN3N)

Details the connections and functions of the CN3N connector for auto change over.

Silent Mode / Demand Control (CN3D)

Selection of silent mode and demand control via DIP switches.

9-7. HOW TO CHECK THE PARTS

Low temperature thermistors

Checking procedures and resistance values for low-temperature thermistors (TH3, TH6, TH7).

Medium temperature thermistor

Checking procedure and resistance values for the heatsink thermistor (TH8).

High temperature thermistor

Checking procedure and resistance values for the discharge/compressor thermistor (TH4).

HIGH PRESSURE SENSOR

Checking procedure and voltage output for the high-pressure sensor (63HS).

10 ELECTRICAL WIRING

10-1. OVERVIEW OF POWER WIRING

General notes and warnings regarding power wiring for the system.

10-2. WIRE DIAMETER AND MAIN POWER SWITCH CAPACITY

Specifications for wire diameter and main power switch capacity.

10-3. DESIGN FOR CONTROL WIRING

Guidelines for selecting and wiring control cables for the system.

10-3-1. Selection number of control wires

Determining the number of control wires based on system configuration.

10-3-2. Control signal wires

Specifications for transmission cable types, diameter, and length.

10-3-3. M-NET Remote controller wiring

Wiring specifications for M-NET remote controllers.

10-3-4. MA Remote control cables

Cable specifications for MA remote controllers.

10-4. SYSTEM SWITCH SETTING

Procedure for setting system addresses using switches on each unit.

10-5. EXAMPLE EXTERNAL WIRING DIAGRAM FOR A BASIC SYSTEM

Example wiring diagram for a basic system with M-NET remote controller.

11 REFRIGERANT PIPING TASKS

11-1. REFRIGERANT PIPING SYSTEM

Details on refrigerant piping system design and permissible lengths.

■ Selecting the Refrigerant Branch Kit

Guidance on selecting the appropriate refrigerant branch kit.

■ Select Each Section of Refrigerant Piping

Selecting the correct piping diameter for each section of the system.

■ Additional refrigerant charge

Procedure for calculating and adding refrigerant based on piping length.

12 DISASSEMBLY PROCEDURE

1. Removing the service panel and top panel

Instructions for removing the service and top panels.

2. Removing the fan motor (MF1, MF2)

Steps to remove the fan motor from the outdoor unit.

3. Removing the electrical parts box

Procedure for removing the electrical parts box.

7. Removing the 4-way valve coil (21S4)

Steps to remove the 4-way valve coil.

8. Removing the 4-way valve

Procedure for removing the 4-way valve assembly.

9. Removing bypass valve coil (SV1) and bypass valve

Steps to remove the bypass valve coil and bypass valve.

10. Removing the high pressure switch (63H) and low pressure switch (63L)

Procedure for removing high and low pressure switches.

11. Removing the high pressure sensor (63HS)

Steps to remove the high pressure sensor.

12. Removing the compressor (MC)

Procedure for removing the compressor.

13. Removing the accumulator

Steps to remove the accumulator.

4. Removing the thermistor <Low pressure saturated temp.> (TH6)

Steps to remove the low pressure saturated temperature thermistor (TH6).

5. Removing the thermistor <Outdoor> (TH7)

Steps to remove the outdoor temperature thermistor (TH7).

6. Removing the thermistor <Outdoor pipe> (TH3) and thermistor <Discharge/Compressor> (TH4)

Steps to remove outdoor pipe and discharge/compressor thermistors.

12. Removing the reactors (ACL1, ACL2, ACL3)

Procedure for removing reactors.

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Mitsubishi Electric PUMY-P125YHMB User Manual

Table of Contents

Questions and Answers:

Mitsubishi Electric PUMY-P125YHMB Specifications

Summary

1 TECHNICAL CHANGE

2 SAFETY PRECAUTION

2-1. CAUTIONS RELATED TO NEW REFRIGERANT

2-2. PRECAUTIONS FOR SALT PROOF TYPE "-BS" MODEL

3 UNIT OVERVIEW

3-1. UNIT CONSTRUCTION

3-2. UNIT SPECIFICATIONS

4 SPECIFICATIONS

5 DATA

5-1. COOLING AND HEATING CAPACITY AND CHARACTERISTICS

5-2. STANDARD CAPACITY DIAGRAM

6 OUTLINES AND DIMENSIONS

Piping Knockout Hole Details

7 WIRING DIAGRAM

Cautions when Servicing

Self-diagnosis function

8 NECESSARY CONDITIONS FOR SYSTEM CONSTRUCTION

8-1. TRANSMISSION SYSTEM SETUP

8-2. REFRIGERANT SYSTEM DIAGRAM

8-3. SYSTEM CONTROL

9 TROUBLESHOOTING

9-1. CHECK POINTS FOR TEST RUN

9-1-2. Special Function Operation and Settings (for M-NET Remote Controller)

9-1-3. Countermeasures for Error During Test Run

9-5. INTERNAL SWITCH FUNCTION TABLE

9-6. OUTDOOR UNIT INPUT/OUTPUT CONNECTOR

State (CN51)

Auto change over (CN3N)

Silent Mode / Demand Control (CN3D)

9-7. HOW TO CHECK THE PARTS

Low temperature thermistors

Medium temperature thermistor

High temperature thermistor

HIGH PRESSURE SENSOR

10 ELECTRICAL WIRING

10-1. OVERVIEW OF POWER WIRING

10-2. WIRE DIAMETER AND MAIN POWER SWITCH CAPACITY

10-3. DESIGN FOR CONTROL WIRING

10-3-1. Selection number of control wires

10-3-2. Control signal wires

10-3-3. M-NET Remote controller wiring

10-3-4. MA Remote control cables

10-4. SYSTEM SWITCH SETTING

10-5. EXAMPLE EXTERNAL WIRING DIAGRAM FOR A BASIC SYSTEM

11 REFRIGERANT PIPING TASKS

11-1. REFRIGERANT PIPING SYSTEM

■ Selecting the Refrigerant Branch Kit

■ Select Each Section of Refrigerant Piping

■ Additional refrigerant charge

12 DISASSEMBLY PROCEDURE

1. Removing the service panel and top panel

2. Removing the fan motor (MF1, MF2)

3. Removing the electrical parts box

7. Removing the 4-way valve coil (21S4)

8. Removing the 4-way valve

9. Removing bypass valve coil (SV1) and bypass valve

10. Removing the high pressure switch (63H) and low pressure switch (63L)

11. Removing the high pressure sensor (63HS)

12. Removing the compressor (MC)

13. Removing the accumulator

4. Removing the thermistor <Low pressure saturated temp.> (TH6)

5. Removing the thermistor <Outdoor> (TH7)

6. Removing the thermistor <Outdoor pipe> (TH3) and thermistor <Discharge/Compressor> (TH4)

12. Removing the reactors (ACL1, ACL2, ACL3)

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