Toshiba MMY-MAP1604T8-SG

Questions and Answers

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hdavisNov 7, 2025
What to do if my Toshiba MMY-MAP1604T8-SG Air Conditioner isn't responding to the remote but there's no check code?
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  Hunter CruzNov 8, 2025
  If your Toshiba Air Conditioner unit isn't responding to the indoor remote controller, but there's no check code on the header unit's interface PC board, consider these possibilities: * The communication line between the indoor and outdoor units might not be connected. Modify the wiring. * The line address and indoor address may not be set. Set up the address. * If in indoor group control, the power of the header unit of the group might not be turned on. Turn on the power. * A group address might be set to the follower unit for individual control. Set the group address to “0” in the case of individual control. * The power might not be turned on. Turn on the power. * The indoor remote controller might not be connected with a wire. Modify the wiring. * There might be miswiring...
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Jennifer StewartNov 17, 2025
Why does my Toshiba MMY-MAP1604T8-SG Air Conditioner show fewer connected units than expected after address setup?
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  Jacob FerrellNov 17, 2025
  If, after setting up the addresses on your Toshiba Air Conditioner, the number of connected outdoor or indoor units displayed is lower than expected, it could be due to: * Miswiring or an unconnected wire in the communication lines between outdoor units. After modifying the wiring, set up the addresses again and check the number of connected outdoor units. * Miswiring or an unconnected wire in the communication lines between indoor units. After modifying the wiring, set up the addresses again and check the number of connected indoor units. * The indoor remote controller is not connected with wire or there is miswiring of the indoor remote controller. Use the main indoor remote controller connected to a group, start a test operation, specify the unit that is not operating (the unit n...
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Emily PittmanNov 27, 2025
Why does my Toshiba MMY-MAP1604T8-SG remote controller display a check code?
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  charlesmcintoshNov 28, 2025
  If a check code is displayed on your Toshiba Air Conditioner's remote controller, it could be due to several reasons: * The outdoor power might be off, so ensure the header outdoor unit power is on. * There might be an address setup error. In this case, set up the address again. * There could be no outdoor terminal resistance, or there might be two or more resistances. Check SW30 bit 2 of the header unit. If there is no connection between multiple refrigerant lines, SW30 bit 2 is on. If there is a connection between multiple refrigerant lines, SW30 bit 2 of the connected header unit is turned on only for one line. * It's possible there's a transmission circuit error at the interface side, which would require replacing the interface PC board. * Communication from all the indoor u...

Summary

Wiring Diagrams

1-1. Outdoor Unit

Provides wiring diagrams for the outdoor unit.

1-2. Indoor Unit

Details wiring diagrams for various types of indoor units.

Parts Rating

2-1. Outdoor Unit (50 Hz model: MMY-MAP***4 HT8-E, MAP4 HT8-TR, MAP4 HT8, MAP4 T8-SG)

Lists parts rating for 50Hz outdoor units including Heat Pump and Cooling Only models.

2-2. Outdoor Unit (60 Hz model: MMY-MAP4 HT7)

Lists parts rating for 60Hz outdoor units.

2-3. Outdoor Inverter (50 Hz model: MMY-MAP4 HT8-E, MAP4 HT8-TR, MAP4 HT8, MAP4 T8-SG)

Lists parts rating for 50Hz outdoor inverter units.

2-4. Outdoor Inverter (60 Hz model: MMY-MAP4 HT7)

Lists parts rating for 60Hz outdoor inverter units.

2-5. Indoor Unit

Lists parts rating for various indoor unit types.

2-6. Parts Layout in Outdoor Unit

Diagrams showing the layout of parts within the outdoor unit.

2-7. Parts Layout in Inverter Assembly

Diagrams showing the layout of parts within the inverter assembly.

2-8. Outdoor (Inverter) Print Circuit Board

Identification and layout of print circuit boards in the outdoor inverter unit.

Refrigerant Piping Systematic Drawing

Combined Refrigerant Piping System Schematic Diagrams

Control Outline

6 Applied Control and Functions (including Circuit Configuration)

Details on applied control functions and circuit configurations for indoor and outdoor units.

6-1. Indoor Controller Block Diagram

6-1-1. When Main (Sub) Remote Controller Connected

Block diagram for indoor unit when main/sub remote controller is connected.

6-1-2. When Wireless Remote Controller Kit Connected

Block diagram for indoor unit when wireless remote controller kit is connected.

6-1-3. When Both Main (Sub) Remote Controller and Wireless Remote Controller Kit Connected

Block diagram for indoor unit with both wired and wireless controllers connected.

6-2. Indoor Printed Circuit Board

6-3. Optional Connector Specifications of Indoor P.C. Board

6-4. Test Operation of Indoor Unit

6-5. Method to Set Indoor Unit Function DN Code

6-6. Applied Control of Indoor Unit

6-7. Applied control for Outdoor Unit

6-7-1. Outdoor Fan High Static Pressure Shift

Procedure for adjusting outdoor fan speed for high static pressure applications.

6-7-2. Priority Operation Mode Setting

Settings for switching between priority cooling and priority heating modes.

6-8. Applied Control of Outdoor Unit

6-8-1. Power peak-cut Control (Standard)

Standard procedure for limiting peak capacity of the outdoor unit.

6-8-2. Power peak-cut Control (Extended)

Extended procedure for limiting peak capacity of the outdoor unit.

6-8-3. Snowfall Fan Control

Function to control outdoor unit fan during snowfall.

6-8-4. External master ON;OFF Control

Function to start/stop the system from the outdoor unit.

6-8-5. Night operation (sound reduction) Control

Function to decrease noise levels during night or other specific times.

6-8-6. Operation Mode Selection Control

Control for selecting operation modes imposed on indoor units.

6-8-7. Error;Operation Output

Output signals for in-operation status and errors.

6-8-8. Compressor Operation Output

Output signals indicating compressor operation status.

6-8-9. Operating Rate Output

Output signals indicating the system's operation rate.

TEST OPERATION

7-1. Procedure and Summary of Test Operation

Overview and step-by-step procedure for executing a test operation.

7-2. Check Items before Test Operation (before powering-on)

Essential checks to perform on wiring and installation before powering the system on.

7-3. Check at Main Power-on

Checks to perform on indoor and outdoor units after main power is turned on.

7-4. Address Setup

Procedure for setting system addresses for indoor and outdoor units.

Troubleshooting in Test Operation

7-5-1. A Check Code Is Displayed on the Remote Controller

Troubleshooting steps when a check code appears on the remote controller.

7-5-2. Operation from the indoor remote controller is not accepted, and a check code is displayed on the 7-segment display of the interface PC board of the header unit.

Troubleshooting when operation is not accepted and a check code is shown on the header unit's 7-segment display.

7-5-3. There is no display of a check code on the 7-segment display on the interface PC board of the header unit, although there is indoor unit that is not accepting operation from the indoor remote controller.

Troubleshooting when no check code is displayed, but indoor units are unresponsive.

7-5-4. In checking the number of connected outdoor units and connected indoor units after address setup, a lower number of connected units is displayed. (There are outdoor;indoor units that do not operate in a test operation.)

Troubleshooting when the number of detected units is lower than expected after address setup.

Test Operation Check

7-6-1. Fan Check

Procedure for checking the fan operation of indoor units.

7-6-2. Cooling;Heating Test Operation Check

Procedure for checking cooling and heating test operations on indoor and outdoor units.

Service Support Function

7-7-1. Check Function for Connecting of Refrigerant and Control Lines

Function to check for misconnections in refrigerant and control lines.

7-7-2. Function to Start;Stop (ON;OFF) Indoor Unit from Outdoor Unit

Function to start or stop indoor units collectively or individually from outdoor unit switches.

7-7-3. Error Clearing Function

Procedures for clearing errors from the remote controller or via interface board switches.

7-7-4. Remote Controller Distinction Function

Function to distinguish connected remote controllers for refrigerant circuit systems.

7-7-5. Pulse Motor Valve (PMV) Forced Open;Close Function in Indoor Unit

Function to force open or close indoor PMV for 2 minutes using interface board switches.

7-7-6. Pulse Motor Valve (PMV) Forced Open Fully;Close fully Function in Outdoor Unit

Function to force open or close PMV1, PMV2, PMV4 in outdoor units for 2 minutes.

7-7-7. Solenoid Valve Forced Open;Close Function in Outdoor Unit

Function to force open or close each solenoid valve in the outdoor unit for checking.

7-7-8. Fan Operation Check in Outdoor Unit

Function to check outdoor fan operation and control fan speed.

7-7-9. Abnormal Outdoor Unit Discrimination Method By Fan Operating Function

Function to discriminate abnormal outdoor units by forcing fan operation.

7-7-10. Manual Adjustment Function of Outside Temperature (TO) Sensor

Function to manually fix the TO sensor value when the unit stops abnormally.

7-7-11. Monitor Function of Remote Controller Switch

Function to monitor sensor temperature or operation status via remote controller.

TROUBLESHOOTING

8-1. Overview

General introduction to troubleshooting procedures and required tools.

8-2. Troubleshooting Method

Method for identifying faults based on check codes displayed on various devices.

8-3. Troubleshooting Based on Information Displayed on Remote Controller

Troubleshooting guide based on information displayed on the remote controller.

8-4. Check Codes Displayed on Remote Controller and SMMS-i Outdoor Unit (7-Segment Display on I;F Board) and Locations to Be Checked

List of check codes and their corresponding locations for troubleshooting.

8-5. Diagnosis procedure for each check code

Diagnostic flowcharts for various check codes.

8-6. 7-Segment Display Function

Explanation of the 7-segment display function for checking operational status.

8-7. Oil Level Judgment Display

Display and interpretation of current compressor oil level judgment results.

8-8. Leakage;Clogging of Refrigerating Cycle Circuit

List of check codes for leakage or clogging in the refrigerating cycle or oil circuit.

8-9. Sensor Characteristics

Graphs and tables showing sensor resistance characteristics.

8-10. Pressure Sensor Output Check

Procedure for checking the output voltage of Pd and Ps pressure sensors.

BACKUP OPERATION (EMERGENCY OPERATION)

9-1. Note for Backup Operation

Important notes regarding backup operation methods based on fault contents.

9-2. Compressor Backup Operation Setting

Procedure for setting compressor backup operation when a compressor fails.

9-3. Outdoor Unit Backup Operation Setting

Procedure for setting outdoor unit backup operation in multi-unit systems.

9-4. Cooling-Season Outdoor Unit Backup Operation Setting

Procedure for backup operation specifically for cooling-season failures.

OUTDOOR UNIT REFRIGERANT RECOVERY METHOD

10-1. Refrigerant Recovery from Failed Outdoor Unit (Pump-Down)

Procedure for recovering refrigerant from a failed outdoor unit using pump-down.

10-2. How to Operate System While Failed Outdoor Unit Being Repaired

Procedure to operate the system by adjusting refrigerant amount after recovery.

10-3. Work procedure after Repair

Procedure to follow after completing repair work and vacuuming.

REPLACING COMPRESSORS

11-1. Compressor Replacement Procedure (Outline)

General outline for replacing a compressor.

11-2. Replacement of Compressors

Detailed procedures for replacing compressors, including oil adjustment.

11-3. Check Procedure to Search Cause of Compressor Oil Shortage

Procedure to diagnose causes of compressor oil shortage.

P.C. BOARD EXCHANGE PROCEDURES

13-1. Replacement of Indoor P.C. Boards

Procedures for replacing indoor unit P.C. boards, including EEPROM handling.

13-2. Replacement of Outdoor P.C. Boards

List of service P.C. boards and their configurations for outdoor units.

EXPLODED DIAGRAM;PARTS PRICE LIST

SMMS-i OUTDOOR UNIT MMY-MAP0804 HT8(Z)(ZG)-E, MMY-MAP1004 HT8(Z)(ZG)-E, MMY-MAP1204 HT8(Z)(ZG)-E

Exploded view and parts list for SMMS-i outdoor units (MAP0804, MAP1004, MAP1204) -E models.

SMMS-i INV SERVICE PARTS LIST MMY-MAP0804 HT8(Z)(ZG)-E, MMY-MAP1004 HT8(Z)(ZG)-E, MMY-MAP1204 HT8(Z)(ZG)-E

Service parts list for SMMS-i outdoor units (MAP0804, MAP1004, MAP1204) -E models.

SMMS-i OUTDOOR UNIT MMY-MAP1404 T8(Z)(ZG)-E, MMY-MAP1604 T8(Z)(ZG)-E

Exploded view and parts list for SMMS-i outdoor units (MAP1404, MAP1604) -E models.

SMMS-i INV SERVICE PARTS LIST MMY-MAP1404 T8(Z)(ZG)-E, MMY-MAP1604 T8(Z)(ZG)-E

Service parts list for SMMS-i outdoor units (MAP1404, MAP1604) -E models.

SMMS-i OUTDOOR UNIT MMY-MAP1404 HT7(Z)(ZG), MMY-MAP1604 HT7(Z)(ZG)

Exploded view and parts list for SMMS-i outdoor units (MAP1404, MAP1604) -T7 models.

SMMS-i INV SERVICE PARTS LIST MMY-MAP1404 HT7(Z)(ZG), MMY-MAP1604 HT7(Z)(ZG)

Service parts list for SMMS-i outdoor units (MAP1404, MAP1604) -T7 models.

SMMS-i OUTDOOR UNIT MMY-MAP0804 T8-SG, MMY-MAP1004 T8-SG, MMY-MAP1204 T8-SG

Exploded view and parts list for SMMS-i outdoor units (MAP0804, MAP1004, MAP1204) -SG models.

SMMS-i INV SERVICE PARTS LIST MMY-MAP0804 T8-SG, MMY-MAP1004 T8-SG, MMY-MAP1204 T8-SG

Service parts list for SMMS-i outdoor units (MAP0804, MAP1004, MAP1204) -SG models.

SMMS-i OUTDOOR UNIT MMY-MAP1404 HT8(Z)(ZG)-TR, MMY-MAP1604 HT8(Z)(ZG)-TR

Exploded view and parts list for SMMS-i outdoor units (MAP1404, MAP1604) -TR models.

SMMS-i INV SERVICE PARTS LIST MMY-MAP1404 HT8(Z)(ZG)-TR, MMY-MAP1604 HT8(Z)(ZG)-TR

Service parts list for SMMS-i outdoor units (MAP1404, MAP1604) -TR models.

SMMS-i OUTDOOR UNIT MMY-MAP1404 HT7(Z)(ZG), MMY-MAP1604 HT7(Z)(ZG)

Exploded view and parts list for SMMS-i outdoor units (MAP1404, MAP1604) -T7 models.

SMMS-i INV SERVICE PARTS LIST MMY-MAP1404 HT7(Z)(ZG), MMY-MAP1604 HT7(Z)(ZG)

Service parts list for SMMS-i outdoor units (MAP1404, MAP1604) -T7 models.