Toshiba MMY-MAP1204T8P User Manual (English)

Questions and Answers:

G
Grant LunaAug 8, 2025
What to do if the Toshiba MMY-MAP1204T8P Air Conditioner indoor remote controller is not accepted and a check code is displayed?
- R
  Roy ParkAug 8, 2025
  If the indoor remote controller isn't working and a check code appears on the interface PC board of the header unit, the issue might stem from unset addresses or incorrect power settings. Start by setting up the addresses for the line and indoor units. If you're using group control, make sure a group address is set up. Also, confirm that the indoor unit power is turned on, ensuring you power on the indoor units before the outdoor units. Finally, check that the indoor/outdoor communication line is correctly connected to the U1/U2 terminal of the header unit.
K
Kelly JonesAug 17, 2025
What to do if my Toshiba Air Conditioner is not accepting operation from the indoor remote controller?
- C
  Catherine JohnsonAug 17, 2025
  If your Toshiba Air Conditioner indoor unit isn't responding to the remote controller and there's no check code on the header unit's interface PC board, the problem likely lies in the communication wiring or address settings. First, check the communication line between the indoor and outdoor units and modify the wiring if necessary. Next, ensure that both the line address and indoor address are correctly set for the unit that's not responding. If you are using indoor group control, make sure that the power of the header unit of the group is turned on. If the unit is under individual control, verify that the group address is set to “0”. Finally, confirm that the power is turned on for the unit and that the indoor remote controller is properly wired.
C
Christopher FaulknerAug 28, 2025
Why does my Toshiba MMY-MAP1204T8P display a lower number of connected units after address setup?
- P
  Patrick JonesAug 28, 2025
  If you're encountering a situation where a lower number of connected units is displayed after address setup, it might be due to miswiring or unconnected wires in the communication lines. * For outdoor units, check the communication lines between them. If you find any issues, correct the wiring, set up the addresses again, and then verify the number of connected outdoor units. * Similarly, inspect the communication lines between indoor units. Correct any miswiring, set up the addresses again, and check the number of connected indoor units. Also, verify the wiring of the indoor remote controller.

Toshiba MMY-MAP1204T8P Specifications

General

Brand	Toshiba
Model	MMY-MAP1204T8P
Category	Air Conditioner
Language	English

Summary

Safety Caution

Definition of Qualified Installer or Qualified Service Person

Defines qualifications and knowledge required for installers and service personnel.

Definition of Protective Gear

Details on necessary protective gear for various work tasks.

New Refrigerant (R410A)

Wiring Diagrams

1-1. Outdoor Unit

Wiring diagrams for various outdoor unit models.

1-2. Indoor Unit

Wiring diagrams for various indoor unit types.

1-2-1. 4-way Cassette Type

Wiring diagram for the 4-way cassette indoor unit.

1-2-2. Compact 4-way Cassette Type

Wiring diagram for the compact 4-way cassette indoor unit.

1-2-3. 1-way Cassette Type (Compact type)

Wiring diagram for the 1-way cassette (compact type) indoor unit.

1-2-4. 1-way Cassette Type SH series

Wiring diagram for the 1-way cassette SH series indoor unit.

1-2-5. 2-way Cassette Type 2 series

Wiring diagram for the 2-way cassette type 2 series indoor unit.

1-2-6. Concealed Duct Standard Type

Wiring diagram for the concealed duct standard type indoor unit.

1-2-7. Concealed Duct Standard Type 6 series

Wiring diagram for the concealed duct standard type 6 series indoor unit.

1-2-8. Concealed Duct High Static Pressure Type

Wiring diagram for the concealed duct high static pressure type indoor unit.

1-2-9. Slim Duct Type

Wiring diagram for the slim duct type indoor unit.

1-2-10. Slim Duct Type (AP024, AP027)

Wiring diagram for slim duct type models AP024 and AP027.

1-2-11. Ceiling Type

Wiring diagram for the ceiling type indoor unit.

1-2-12. High Wall Type 4MH series

Wiring diagram for the high wall type 4MH series indoor unit.

1-2-13. High Wall Type 3 series

Wiring diagram for the high wall type 3 series indoor unit.

1-2-14. Floor Standing Cabinet Type

Wiring diagram for the floor standing cabinet type indoor unit.

1-2-15. Floor Standing Concealed Type

Wiring diagram for the floor standing concealed type indoor unit.

1-2-16. Floor Standing Type

Wiring diagram for the floor standing type indoor unit.

1-2-17. Air to Air Heat Exchanger with DX Coil Unit

Wiring diagram for air to air heat exchanger with DX coil unit.

1-2-18. Fresh Air Intake Indoor Unit

Wiring diagram for the fresh air intake indoor unit.

Parts Rating

2-1. Outdoor Unit (50Hz model: MMY-MAP***4T8P*)

Parts rating for 50Hz outdoor units.

2-2. Outdoor Unit (60Hz model: MMY-MAP***4HT7*P)

Parts rating for 60Hz outdoor units.

2-3. Outdoor Inverter (50Hz model: MMY-MAP***4T8P*)

Parts rating for 50Hz outdoor inverter units.

2-4. Outdoor Inverter (60Hz model: MMY-MAP***4HT7*P)

Parts rating for 60Hz outdoor inverter units.

2-5. Parts Layout in Outdoor Unit

Visual layout of components within the outdoor unit.

2-6. Parts Layout in Inverter Assembly

Visual layout of components within the inverter assembly.

2-7. Outdoor (Inverter) Print Circuit Board

Detailed view of outdoor inverter print circuit boards.

2-7-1. Interface P.C. board (MCC-1606)

Layout of the interface PC board (MCC-1606).

2-7-2. Inverter P.C. board for compressor (MCC-1596) A3-IPDU

Layout of the compressor inverter PC board (MCC-1596).

2-7-3. Inverter P.C. board for fan (MCC-1610)

Layout of the fan inverter PC board (MCC-1610).

Refrigerant Piping Systematic Drawing

4 Combined Refrigerant Piping System Schematic Diagrams

Schematic diagrams illustrating refrigerant flow for various operating conditions.

4-1. Normal Operation (COOL Mode / DEFROST Mode) - High Outside Air Temperature (Roughly 20°C or Above)

Refrigerant flow during normal operation at high outside temperatures.

4-2. Normal Operation (COOL Mode) - Low Outside Air Temperature (Roughly Below 20°C)

Refrigerant flow during normal operation at low outside temperatures.

4-3. Normal Operation (HEAT Mode)

Refrigerant flow during normal heating operation.

4-4. Emergency Operation (Cooling Operation under Header Outdoor Unit Backup Scenario)

Refrigerant flow during cooling emergency operation with header unit backup.

4-5. Emergency Operation (Heating Operation under Header Outdoor Unit Backup Scenario)

Refrigerant flow during heating emergency operation with header unit backup.

4-6. Refrigerant Recovery from Failed Outdoor Unit (Pump-Down Operation under Follower Outdoor Unit Backup Scenario)

Refrigerant recovery procedure during backup operation when an outdoor unit fails.

Control Outline

Indoor Unit Control Specifications

Specifications and settings for indoor unit control.

5 Fan speed control

Control of fan speed in AUTO mode based on temperature differences.

6 Cold air discharge prevention control

Control to prevent cold air discharge during heating and defrosting.

7 Freeze prevention control (low temp. release)

Control to prevent freezing during cooling operation under low temperatures.

8 Cooling oil (refrigerant) recovery control

Control for collecting and returning refrigerating oil during cooling operation.

9 Heating refrigerant (oil) recovery control

Control for recovering refrigerant and oil during heating operation.

10 Defrosting control

Control procedures for defrosting the outdoor unit.

11 Short intermittent operation compensation control

Control to compensate for short intermittent operations.

12 Drain pump control

Control logic for the drain pump operation.

13 Elimination of residual heat

Function to eliminate residual heat after heating operation.

14 Filter sign display

Display of filter replacement status and reset function.

15 Operation standby

Indicates system status like operation standby and heating standby.

Outdoor Unit

1. Pulse motor valve (PMV) control

Control logic for PMV1, 2, and PMV4, including opening and pulse counts.

2. Outdoor fan control

Control strategies for outdoor fan speed in cooling and heating modes.

3. Capacity control

Control logic for compressor operation based on capacity demand and rotation.

4. Oil level detection control

5. Oil equation control

6. Refrigerant/oil recovery control

7. Defrosting control (reverse defrosting method)

8. Release valve control

1. SV2 gas balance control

Control for SV2 to achieve gas balance when compressors are off.

2. SV2 high pressure release control

Control for SV2 to mitigate pressure rise during low-speed operation.

3. SV2 low pressure release control

Control for SV2 to prevent rapid pressure fall during transient operation.

4. SV41, 42, 43 low pressure release control

Low pressure release control for SV41, 42, 43 to protect against low pressure.

5. SV5 high pressure release control

Control for SV5 to mitigate pressure rise in heating operation.

9. High pressure release compressor shutdown control

10. Case heater control

11. A3-IPDU control

1. Current release control

Control to prevent inverter input current from exceeding limits.

2. Heat sink temperature detection control

Control to protect IGBT from overheating via heat sink temperature.

3. Overcurrent protection control

Protection against abnormal current by shutting down the compressor.

4. High pressure SW control

Control triggered by high-pressure SW activation.

6 Applied Control and Functions (including Circuit Configuration)

6-1. Indoor Controller Block Diagram

Block diagram of indoor controller showing connections and components.

6-1-1. When Wired (Simple) Remote Controller Connected

Wiring diagram for simple wired remote controller connection.

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

Wiring diagram for wireless remote controller kit connection.

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

Wiring diagram for combined wired and wireless remote controller setup.

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

Function to increase outdoor fan speed for duct installation with static pressure.

6-7-2. Priority Operation Mode Setting

Setting priority for cooling or heating operations among indoor units.

6-8. Applied Control of Outdoor Unit

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

Standard control to limit peak capacity of the outdoor unit via external signal.

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

Extended control for limiting peak capacity using external signals and relay contacts.

6-8-3. Snowfall Fan Control

Function to turn on the outdoor unit fan based on a snowfall signal.

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

Function to start or stop the system from the outdoor unit via external signals.

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

Function to reduce noise by reducing system capacity during night operations.

6-8-6. Operation Mode Selection Control

Allows selection of operation modes (COOL/HEAT) imposed on indoor units.

6-8-7. Error/Operation Output

Output signals for indicating operation status and errors.

6-8-8. Compressor Operation Output

Output signals indicating the operation status of each compressor.

6-8-9. Operating Rate Output

Output signals representing the system's operating rate.

TEST OPERATION

7-1. Procedure and Summary of Test Operation

General steps for performing a test operation and troubleshooting.

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

Essential checks before powering on the system for test operation.

7-3. Check at Main Power-on

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

7-4. Address Setup

Procedures for setting unit addresses for system operation.

7-4-3. Address Setup Procedure

Step-by-step guide for setting addresses automatically or manually.

7-4-4. Check after Address Setup when Central Control System Is Connected

Verification steps after address setup with a central control system.

7-5. Troubleshooting in Test Operation

Common issues and solutions during test operation.

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

Troubleshooting check codes displayed on the indoor remote controller.

7-6. Test Operation Check

Procedures for checking fan operation and cooling/heating test operations.

7-6-1. Fan Check

Step-by-step guide to check fan operation and identify issues.

7-6-2. Single cooling/Single heating Test Operation Check

Procedures for performing single cooling and single heating test operations.

7-7. Service Support Function

Functions for service technicians to check and control the system.

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

Function to check for misconnections in refrigerant pipes and control lines.

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

Controls indoor unit operation (start/stop, mode) directly from the outdoor unit.

7-7-3. Error Clearing Function

Procedures to clear detected errors from remote controllers or outdoor unit interface.

7-7-4. Remote Controller Distinction Function

Function to distinguish connected remote controllers using switches.

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

Function to force open or close PMV in indoor units for 2 minutes.

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

Function to force PMV open or close fully in outdoor units for 2 minutes.

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

Function to force open/close solenoid valves in outdoor units for checking.

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

Function to check outdoor fan operation and speed.

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

Method to discriminate faulty outdoor units based on fan operation.

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

Manual adjustment of the outside temperature sensor value.

TROUBLESHOOTING

8-1. Overview

General introduction to troubleshooting procedures and required tools.

8-2. Troubleshooting Method

Analysis of check codes detected by various devices for fault diagnosis.

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

Diagnosis based on check codes 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

Mapping of check codes, locations, causes, and troubleshooting steps.

8-5. Diagnosis procedure for each check code

Flowcharts for diagnosing specific check codes.

8-6. 7-Segment Display Function

Explanation of the 7-segment display on the outdoor unit interface PC board.

8-7. Oil Level Judgment Display

Procedure to check compressor oil level judgment results via outdoor unit switches.

8-8. Leakage/Clogging of Refrigerating Cycle Circuit

Lists check codes related to refrigerant cycle and oil circuit issues.

8-9. Sensor Characteristics

Electrical characteristics (resistance vs. temperature) of various sensors used in the unit.

8-10. Pressure Sensor Output Check

Voltage and pressure characteristics for Pd and Ps sensors.

BACKUP OPERATION (EMERGENCY OPERATION)

9-1. Note for Backup Operation

Important notes and guidelines for performing backup operation.

9-2. Compressor Backup Operation Setting

Procedure for setting up compressor backup operation using DIP switches.

9-3. Outdoor Unit Backup Operation Setting

Procedure for setting up outdoor unit backup operation when a unit fails.

9-3-1. Follower outdoor unit backup operation setting (failure of follower outdoor unit)

Steps for setting backup operation when a follower outdoor unit fails.

9-3-2. Header outdoor unit backup operation setting (failure of header outdoor unit)

Steps for setting backup operation when the header outdoor unit fails.

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

Setting up backup operation specifically for cooling-season.

OUTDOOR UNIT REFRIGERANT RECOVERY METHOD

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

Procedures for refrigerant recovery using pump-down method.

10-1-2. Refrigerant recovery procedure A (Case of no outdoor unit backup operation setting)

Procedure A for refrigerant recovery when no backup operation is set.

10-1-3. Refrigerant recovery procedure B (Case of outdoor unit backup operation setting)

Procedure B for refrigerant recovery when backup operation is set.

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

Guidelines for operating the system while a failed outdoor unit is under repair.

10-3. Work procedure after Repair

Steps to follow after repairing an outdoor unit, including vacuuming and charging.

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.

OUTDOOR UNIT PARTS REPLACEMENT METHODS

1 Cabinet

Procedure for detaching and attaching the outdoor unit cabinet.

2 Propeller fan Fan motor

Procedure for replacing the propeller fan and fan motor.

3 Heat exchanger

Procedure for detaching and installing heat exchangers.

4 Inverter assembly

Procedure for removing and installing the inverter assembly.

5 Reactor assembly

Procedure for replacing the reactor assembly.

6 2-way valve coils Pressure sensors locations

Locations and replacement procedures for 2-way valve coils and pressure sensors.

7 Temperature sensors - locations and identification colors

Locations and identification of temperature sensors.

8 Pipe fixing rubber - detachment/attachment (common)

Procedure for detaching and attaching pipe fixing rubber.

9 4-way valve - detachment/attachment

Procedure for detaching and attaching the 4-way valve.

P.C. BOARD EXCHANGE PROCEDURES

Indoor Unit

Procedures for replacing indoor unit PC boards.

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

Detailed procedures for replacing indoor unit PC boards.

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

Procedures for replacing outdoor unit PC boards.

13-2-1. List of service P.C. boards

List of service PC boards and their types.

13-2-2. Configuration of inverter assembly

Configuration of the inverter assembly.

13-2-3. Interface board (MCC-1606) replacement method

Method for replacing the interface board (MCC-1606).

13-2-4. Comp-IPDU P.C. Board (MCC-1596) Replacement Procedure

Procedure for replacing the compressor IPDU P.C. board (MCC-1596).

13-2-5. Fan IPDU P.C. Board (MCC-1610) Replacement Procedure

Procedure for replacing the fan IPDU P.C. board (MCC-1610).

13-2-6. Noise Filter P.C. Board (MCC-1608 A, B) Replacement Procedure

Procedure for replacing the noise filter P.C. board.

EXPLODED DIAGRAM/PARTS LIST

Related product manuals

Toshiba MMY-MAP1204T8

22 pages

Toshiba MMY-MAP1204T8-E

34 pages

Toshiba MMY-MAP1204T8-SG

370 pages

Toshiba MMY-MAP1204T8P-T

323 pages

Toshiba MMY-MAP1204T8P-SG

325 pages

Toshiba MMY-MAP1204T8(J)P-E