Toshiba Mmy-map1004ft8-e Service Manual =link= Here

The SHRM-i 3-pipe configuration offers significant design flexibility compared to conventional 2-pipe systems:

Fix: Verify continuity on the U1/U2 communication loop. Check for external electromagnetic interference (EMI) or loose terminal screws. Ensure shielding is grounded properly at the outdoor chassis only. Electrical Wiring and PCB Configuration

Ground the shield loop at the outdoor unit side only to eliminate electromagnetic interference. Do not close loop-to-loop shields to ground at multiple points. Advanced Troubleshooting and Error Codes toshiba mmy-map1004ft8-e service manual

Since I cannot generate a file download, you can usually find the full manual at the following sources:

Inspect the discharge pipe temperature sensor and connection. L07 / L08 (Outdoor unit capacity mismatch): Verify if the correct indoor units are paired with the MMY-MAP1004FT8-E Go to product viewer dialog for this item. 5. Setting Up and Servicing via Sub-Display Electrical Wiring and PCB Configuration Ground the shield

Ensure phase rotation is correct; incorrect rotation triggers an instantaneous safety fault. Control and Communication (U1/U2 Network) Non-polar 2-core shielded cable. Wire Specification: 2-core stranded wire, minimum 1.5 mm².

Outdoor unit runs, but indoor units blow cold air when set to heat. Manual Solution: The logic flowchart shows that the 4-way reversing valve needs 30 seconds to shift. If not, the manual instructs how to manually energize the solenoid using the "Test Run" function (bypassing the main CPU) to confirm valve function. L07 / L08 (Outdoor unit capacity mismatch): Verify

Perform a vacuum hold test for at least 30 minutes to verify system tightness. Additional Charge Calculation