Mitsubishi Electric MUH-GD80VB

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CONTENTS

1. TECHNICAL CHANGES ··································· 2

2. PART NAMES AND FUNCTIONS ····················· 2

3. SPECIFICATION ················································ 3

4. NOISE CRITERIA CURVES ······························ 3

5. OUTLINES AND DIMENSIONS ························ 4

6. WIRING DIAGRAM ············································ 4

7. REFRIGERANT SYSTEM DIAGRAM ··············· 5

8. PERFORMANCE CURVES ······························· 6

9. ACTUATOR CONTROL ··································· 10

10. SERVICE FUNCTIONS ·····································11

11. TROUBLESHOOTING ······································11

12. DISASSEMBLY INSTRUCTIONS ···················· 18

SERVICE MANUAL

Wireless type

Model

MUH-GD80VB -

SPLIT-TYPE, HEAT PUMP AIR CONDITIONERS

NOTE:

RoHS compliant products have <G> mark on the spec name plate.

HFC

utilized

R410A

OUTDOOR UNIT

No. OBH514

Indoor unit service manual

MSH-GD•VB Series (OBH513)

PARTS CATALOG (OBB514)

Main Page

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This document provides a comprehensive service manual for the Mitsubishi Electric MUH-GD80VB outdoor unit, a split-type, heat pump air conditioner designed for efficient heating and cooling. The unit utilizes HFC R410A refrigerant, aligning with modern environmental standards.

Function Description:

The MUH-GD80VB is an outdoor unit that forms part of a split-type air conditioning system. Its primary function is to provide both cooling and heating capabilities for indoor spaces by transferring heat between the indoor and outdoor environments. In cooling mode, it extracts heat from the indoor air and dissipates it outdoors, while in heating mode, it absorbs heat from the outdoor air and transfers it indoors. The system operates on a single-phase 230 V, 50 Hz power supply.

Important Technical Specifications:

Model: MUH-GD80VB
Power Supply: Single phase, 230 V, 50 Hz
Capacity:
- Cooling: 8.0 kW
- Heating: 9.4 kW
Electrical Data:
- Breaker capacity: 25 A
- Running current (Total): 14.76 A (Cooling), 15.90 A (Heating)
- Power input (Total): 3.325 kW (Cooling), 3.580 kW (Heating)
- Starting current (Total): 98 A
- Power factor (Total): 90%
Coefficient of Performance (C.O.P) / Energy Efficiency Ratio (EER):
- Cooling: 2.41
- Heating: 2.63
Compressor:
- Model: NN37VAAHT
- Output: 2.500 kW
- Compressor motor current: 13.85 A (Cooling), 14.62 A (Heating)
Fan Motor:
- Model: RA6V75-AD
- Output: 0.57 kW
- Dimensions W x H x D: 840 x 850 x 330 mm
Weight: 77 kg
Dehumidification: 4.6 l/h
Air Flow (High/Low): 2,940/1,470 m³/h
Sound Level (High/Low): 55/33 dB
Fan Speed (High/Low): 905/455 rpm
Fan speed regulator: 2
Refrigerant Filling Capacity: 2.40 kg (R410A)
Refrigeration Oil (Model): NEO 22
Refrigerant Piping Length:
- Max. length: 30 m
- Max. height difference: 15 m
- Additional refrigerant charge: 55 g/m for lengths exceeding 7 m.
Operating Conditions (based on ISO 5151):
- Cooling:
  - Indoor: Dry-bulb temperature 27°C, Wet-bulb temperature 19°C
  - Outdoor: Dry-bulb temperature 35°C, Wet-bulb temperature 24°C
- Heating:
  - Indoor: Dry-bulb temperature 20°C, Wet-bulb temperature 15°C
  - Outdoor: Dry-bulb temperature 7°C, Wet-bulb temperature 6°C
- Indoor-Outdoor piping length: 5 m

Usage Features:

The MUH-GD80VB is designed for reliable operation across a range of ambient conditions. The manual details performance curves for cooling capacity, total input, and current consumption under various indoor and outdoor dry-bulb and wet-bulb temperatures. These curves help in understanding the unit's performance characteristics and ensuring optimal operation.

Low Pressure and Outdoor Unit Current Control: The unit employs control mechanisms to manage outdoor unit current based on dry-bulb temperature and relative humidity. This ensures stable operation and prevents overloading.
Heat Operation: Specific conditions for heat operation are provided, including indoor dry-bulb and wet-bulb temperatures, and outdoor dry-bulb and wet-bulb temperatures.
Actuator Control: The manual includes details on the R.V. coil control, which is essential for switching between heating and cooling modes. The 4-way valve reverses for 5 seconds right before compressor start-up in both cooling and heating modes.
Compulsory Defrosting Mode: The unit features a compulsory defrosting mode, which can be activated by short-circuiting specific connectors on the outdoor deicer P.C. board. This is crucial for maintaining heating efficiency in cold conditions. The defrost interval time and defrost finish temperature can be changed via jumper wires.

Maintenance Features:

The service manual provides extensive information for troubleshooting and maintenance, ensuring the longevity and efficient operation of the MUH-GD80VB.

Troubleshooting:
- Basic Checks: Before troubleshooting, users are advised to check power supply voltage, ensure the indoor/outdoor connecting wires are correct, and verify that the air filter is clean.
- Emergency Operation Switch: The manual emphasizes the use of the emergency operation switch on the indoor unit P.C. board for testing and troubleshooting.
- Troubleshooting Flowcharts: Detailed flowcharts are provided for diagnosing issues with the outdoor unit, R.V. coil, and outdoor fan motor. These flowcharts guide technicians through a systematic process of checking power supply, voltage, and component functionality.
- Check of Outdoor Unit: This section outlines steps to diagnose issues with the outdoor unit, including checking compressor operation, voltage across specific terminals, and replacing components like the deicer P.C. board or compressor contactor.
- Check of R.V. Coil: Instructions are given to measure the resistance of the R.V. coil and follow a flowchart to determine if it is disconnected, short-circuited, or requires replacement.
- When OPERATION INDICATOR lamp flashes ON and OFF in every 0.5-second: This section addresses mis-wiring issues, providing steps to check for poor contact or wire disconnection and guiding through the process of replacing the indoor electronic control P.C. board or checking outdoor power supply and connection wiring.
- When OPERATION INDICATOR lamp flashes 10-time. Heating/Cooling doesn't operate: This indicates an issue with the LEV (Expansion valve). The manual provides steps to check LEV operation, verify its proper fit, and measure the resistance of the LEV. A flowchart helps in diagnosing and replacing the deicer P.C. board if necessary.
- When OPERATION INDICATOR lamp flashes 6-time. Thermistors in the outdoor unit are abnormal: This section focuses on checking outdoor thermistors (defrost, discharge temperature, and ambient temperature). It provides instructions on how to measure resistance between specific connectors and compare values to the provided resistance curves. Flowcharts guide the replacement of the deicer P.C. board or the thermistor itself.
Test Point Diagram and Voltage: A detailed diagram of the outdoor deicer P.C. board is included, showing test points and expected DC voltages for various components like the R.V. coil, varistor, and fan motor connector. Resistance curves for defrost, discharge temperature, and ambient temperature thermistors are also provided to aid in diagnosis.
Disassembly Instructions: Comprehensive instructions with accompanying photos are provided for disassembling the MUH-GD80VB unit. This includes:
- Removing the cabinet: Step-by-step guide to remove the service panel, top panel, valve cover, and back panel.
- Removing the deicer P.C. board: Instructions to disconnect connectors and remove the board.
- Removing the propeller and outdoor fan motor: Details on how to remove the propeller nut, align the mark on the propeller and motor shaft, and remove the fan motor.
- Removing the compressor: Instructions to remove the cabinet, relay panel, compressor felt, terminal cover, wires, and recover gas before removing the compressor.

The manual also includes a note about RoHS compliance, indicating that compliant products have a "" mark on the spec name plate. This ensures that the device adheres to environmental regulations regarding hazardous substances.