Revision A: MUZ-A18YV - can be connected to MCFZ-A18WV - MUZ-A24YV - can be connected to SPLIT-TYPE, HEAT PUMP AIR CONDITIONERS MCFZ-A24WV - Please void OB346. utilized SERVICE MANUAL R410A No. OB346 Wireless type REVISED EDITION-A Models MUZ-A18YV - MUZ-A24YV -...
TECHNICAL CHANGES INFORMATION FOR THE AIR CONDITIONER WITH R410A REFRIGERANT • This room air conditioner adopts an HFC refrigerant (R410A) which never destroys the ozone layer. • Pay particular attention to the following points, though the basic installation procedure is same as that for R22 air conditioners.
Page 3
Conversion chart of refrigerant temperature and pressure (MPa [Gauge]) R410A NOTE : The unit of pressure has been changed to MPa on the international system of units(SI unit system). f [Gauge]) The conversion factor is: 1(MPa [Gauge]) =10.2(kgf/f -0.5 -30 -20 -10 1.Tools dedicated for the air conditioner with R410A refrigerant The following tools are required for R410A refrigerant.
Page 4
2 Flaring work and flare nut Flaring work for R410A pipe differs from that for R22 pipe. For details of flaring work, refer to Installation manual “FLARING WORK”. Dimension of flare nut Pipe diameter R410A 6.35 9.52 12.7 15.88 3.Refrigerant oil Apply the special refrigeration oil (accessories: packed with indoor unit) to the flare and the union seat surfaces.
PART NAMES AND FUNCTIONS MUZ-A18YV - ACCESSORIES MUZ-A24YV - MUZ-A26YV - OUTDOOR UNIT Air inlet MUZ-A18YV - (back and side) MUZ-A24YV - Piping MUZ-A26YV - Drain socket Drain hose Drain cap [33 Air outlet Drain outlet SPECIFICATION MUZ-A18YV - MUZ-A18YV -...
Page 6
MUZ-A24YV - MUZ-A24YV - MUZ-A26YV - Outdoor model Indoor model Indoor model Indoor model MSZ-A24YV - MCFZ-A24WV - MSZ-A26YV - Cooling Heating Cooling Heating Cooling Heating Function Single phase Single phase Single phase Power supply 230V,50Hz 230V,50Hz 230V,50Hz Capacity Rated frequency(Min.~Max.) 6.0(0.9~6.7) 6.8(0.9~8.1) 5.5(0.9~6.1)
Page 7
Specifications and rating conditions of main electric parts OUTDOOR UNIT Model MUZ-A18YV - MUZ-A24YV - MUZ-A26YV - Item (CB1,2,3) Smoothing capacitor 560+ 450V (CT1,2) Current transformer ETQ19Z68AY (CT61) Current transformer ETQ19Z53AY (F801, F912) Fuse 250V 3.15A (F911) Fuse 250V 1A...
NOISE CRITERIA CURVES MUZ-A18YV - MUZ-A24YV - MUZ-A26YV - SPEED FUNCTION SPL(dB(A)) LINE COOLING High HEATING Test conditions, Cooling : Dry-bulb temperature 35: Wet-bulb temperature (24:) Heating : Dry-bulb temperature 7: Wet-bulb temperature 6: OUTDOORUNIT NC-70 NC-60 MICROPHONE NC-50 NC-40...
Open as a rule 500mm or more if the back, 350mm or more both sides and top are open Service panel Liquid refrigerant pipe joint Refrigerant pipe (flared) [6.35 (MUZ-A18/A24YV) [9.52 (MUZ-A26YV) Gas refrigerant pipe joint Refrigerant pipe (flared) [12.7 (MUZ-A18YV) [15.88 (MUZ-A24/A26YV)
PERFORMANCE CURVES MUZ-A18YV - MUZ-A24YV - MUZ-A26YV - The standard data contained in these specifications apply only to the operation of the air conditioner under normal conditions. Since operating conditions vary according to the areas where these units are installed. The following information has been provided to clarify the operating characteristics of the air conditioner under the conditions indicated by the performance curve.
Page 15
11.9 12.1 14.4 Outdoor intake air Wet-bulb temperature (:) Outdoor intake air Wet-bulb temperature (:) NOTE:The above curves are for the heating operation without any frost. MUZ-A18YV - MUZ-A18YV - MUZ-A18YV - MUZ-A18YV - Indoor unit : Indoor unit :...
Page 16
OUTDOOR LOW PRESSURE AND OUTDOOR UNIT CURRENT COOL operation 1 Both indoor and outdoor unit are under the Dry-bulb temperature Relative humidity(%) same temperature/humidity condition. 2 Air flow : High speed 3 Operational frequency : 25Hz(MUZ-A18YV) 25Hz(MUZ-A24YV) 24Hz(MUZ-A26YV) MUZ-A18YV - MUZ-A18YV - MUZ-A18YV - MUZ-A18YV -...
ACTUATOR CONTROL MUZ-A18YV - MUZ-A24YV - MUZ-A26YV - 9-1. Outdoor fan motor control The fan motor turns ON/OFF, interlocking with the compressor. [ON] The fan motor turns ON 5 seconds before the compressor starts up. [OFF] The fan motor turns OFF 15 seconds after the compressor has stopped running.
TROUBLESHOOTING MUZ-A18YV - MUZ-A24YV - MUZ-A26YV - 10-1. Cautions on troubleshooting 1. Before troubleshooting, check the following: 1) Check the power supply voltage. 2) Check the indoor/outdoor connecting wire for mis-wiring. 2. Take care the following during servicing. 1) Before servicing the air conditioner, be sure to first turn off the remote controller to stop the main unit, and then after confirming the horizontal vane is closed, turn off the breaker and / or disconnect the power plug.
Page 31
10-2. Instruction of troubleshooting Start Indoor unit Indoor unit Indoor unit operates. OPERATION INDICATOR operates. doesn't receive Outdoor unit doesn't lamp on the indoor unit is Outdoor unit the signal from operate normally. flashing on and off. doesn't remote controller. operate.
Page 32
1. Troubleshooting check table LED 1 (Red) LED 2 (Yellow) Error mode Lighting Lighting Normal Refer to page 35. Symptom: Outdoor unit does not operate. Indication Abnormal point Detecting method Check points LED 1 LED 2 (Red) (Yellow) When the compressor operation has been interrupted by over current protection continuously three times within 1 minute after start-up, or Lighting Twice...
Page 33
Symptom: Outdoor unit operates (The compressor operates at reduced frequency) Indication Abnormal point Detecting method Check points LED 1 LED 2 (Red) (Yellow) Once Lighting Current protection When the outdoor unit input current exceeds 14.5A. Twice Lighting High-pressure protection When the indoor gas pipe temperature exceeds 55˚C during heating. Twice Lighting Defrosting in cooling When the indoor gas pipe temperature falls to 6˚C or below during cooling.
Page 34
2. Trouble criterion of main parts MUZ-A18YV - MUZ-A24YV - MUZ-A26YV - Part name Check method and criterion Measure the resistance using a tester. Defrost thermistor/ (Part temperature : -10°C ~ 40°C) Outdoor heat exchanger Normal abnormal temperature thermistor Open or short-circuit 5kΩ...
Page 35
Outdoor unit does not operate. (LED display: display OFF) A A Check of power supply Start Check the connecting of parts of main power supply circuit. Turn on power supply. Is there voltage of 230V AC in the Check the power supply cable. power supply terminal block? Replace the noise Is the output voltage from the noise...
Page 36
When OPERATION INDICATOR lamp flashes ON and OFF in every 0.5-second. Outdoor unit does’t operate. (LED display: Both LED1 and LED2 lighting) How to check mis-wiring and serial signal error (when outdoor unit does not work) Start • Turn ON the power supply (Indoor/ outdoor unit). •...
Page 37
The cooling operation or heating operation does not operate. (LED display: Both LED1 and LED2 lighting) C C Check of R.V. coil • When heating operation does not work. Start 1. Disconnect the lead wire leading to the compressor. 2. 3 minutes after turning on the power supply, start EMERGENCY OPERATION in HEAT mode.
Page 38
• When cooling, heat exchanger of non-operating indoor unit frosts. • When heating, non-operating indoor unit get warm. D D Check of LEV LED display: LED1 LED2 Lighting Lighting 6 time Goes out Start Turn on power supply to the outdoor unit after checking LEV coil is mounted to the LEV body securely.
Page 39
• When OPERATION INDICATOR lamp flashes 6-time. • When thermistor is abnormal. (When the LED display is a table below.) F F Check of outdoor thermistors Start Disconnect the connector in the electronic control P.C. board (see below table), and Replace the thermistor.
Page 40
• When the operation frequency does not go up from lowest frequency. H H Check of HPS MUZ-A26YV Start 1. Disconnect the connector CN681 in the electronic control P.C. board. 2. Check the resistance of HPS after 1 minutes have passed since the outdoor unit power supply was turned off. Infinity Check the resistance between Replace HPS.
Page 41
MUZ-A18YV - MUZ-A24YV - MUZ-A26YV - Defrost temperature thermistor (RT62) Fin temperature thermistor (RT65) Outdoor heat exchanger temperature thermistor (RT68) Outdoor electronic control P.C. board Discharge temperature thermistor (RT61) 10 20 30 40 50 60 70 80 Temperature (;) 100 110 120 Temperature (;)
Page 42
MUZ-A18YV - MUZ-A24YV - MUZ-A26YV - Noise filter P.C. board CN901 Electronic control CN902 CN903 230V AC board Power board 50Hz Input CN912 R.V. coil 230V AC 230V AC 50Hz Output F911 FUSE F912 FUSE 1A/250V 3.15A/250V NR63 VARISTOR...
Page 43
MUZ-A18YV - MUZ-A24YV - MUZ-A26YV - Power board Connect to the compressor Voltage among phases: 5V to 180V 325-370V DC Output (Red) (–) (White) Connect to the earth Signal reception (From electronic control P.C. board) 5V DC pulse wave Fin temperature thermistor RT65...
2Pull the terminal while pull out the terminal pushing the locking slowly. Locking lever lever. Connector NOTE : MUZ-A18YV - MUZ-A24YV - MUZ-A26YV - These photos are MUZ-A26YV. Other models are almost the same as MUZ-A26YV. OUTDOOR UNIT OPERATING PROCEDURE PHOTOS 1.
Page 45
OPERATING PROCEDURE PHOTOS 2. Removing the inverter assembly, inverter P.C. board Photo 4 and power board Screws of the power board assembly (1) Remove the top panel, cabinet and service panel. (Refer to 1.) (2) Remove the back panel.(Refer to 1.) (3) Disconnect the following connectors;...
Page 46
OPERATING PROCEDURE PHOTOS 4. Removing the defrost thermistor, discharge temper- Photo 5 ature thermistor and outdoor heat exchanger tem - Discharge temperature thermistor perature thermistor (1) Remove the top panel, cabinet and service panel. (Refer to 1.) (2) Remove the back panel. (Refer to 1.) (3) Remove the inverter assembly.
Page 47
OPERATING PROCEDURE PHOTOS 6. Removing the compressor and 4-way valve Photo 8 (1) Remove the top panel, cabinet and service panel. (Refer to 1.) (2) Remove the back panel. (Refer to 1.) (3) Remove the inverter assembly. (Refer to 2.) (4) Recover gas from the refrigerant circuit.
PARTS LIST MUZ-A18YV - MUZ-A24YV - MUZ-A26YV - 12-1. OUTDOOR UNIT STRUCTURAL PARTS, ELECTRICAL PARTS AND FUNCTIONAL PARTS These figures show about MUZ-A26YV.
Page 49
MUZ-A18YV - MUZ-A24YV - MUZ-A26YV - 12-1. OUTDOOR UNIT STRUCTURAL PARTS, ELECTRICAL PARTS AND FUNCTIONAL PARTS Part numbers that are circled are not shown in the illustration. Q'ty/unit Symbol Remarks Part No. Part Name in Wiring MUZ-A18 MUZ-A24 MUZ-A26 Diagram...
Page 50
MUZ-A18YV - MUZ-A24YV - MUZ-A26YV - 12-2. ACCESSORY Q'ty/unit Symbol in Wiring Remarks Part No. Part Name MUZ-A18 MUZ-A24 MUZ-A26 Diagram YV - YV - YV - E02 817 704 DRAIN SOCKET E02 444 705 DRAIN CAP...
Page 52
HEAD OFFICE: MITSUBISHI DENKI BLDG., 2-2-3, MARUNOUCHI, CHIYODA-KU, TOKYO100-8310, JAPAN C C Copyright 2004 MITSUBISHI ELECTRIC ENGINEERING CO.,LTD Distributed in Jun. 2004. No. OB346 REVISED EDITION - A 6 New publication, effective Jun. 2004 Distributed in Apr. 2004. No. OB346 6 Specifications subject to change without notice.
Need help?
Do you have a question about the MUZ-A18YV and is the answer not in the manual?
Questions and answers