What are the current (e.g., fans running but no cooling, completely dead system)?
You might be tempted to rely on general HVAC knowledge or generic troubleshooting guides. That is a dangerous gamble. Here is why the official Toshiba service manual is non-negotiable: toshiba mmy-map1004ft8-e service manual
The main interface PCB on the MMY-MAP1004FT8-E features a 7-segment display that shows active system fault codes. Critical Error Code Matrix Error Code Fault Description Primary Root Cause Corrective Action / Checkpoints Indoor/Outdoor Communication Error Broken connection on U1/U2 bus; lost power to indoor unit. Check indoor unit breakers. Measure DC voltage on U1/U2. E04 Outdoor/Outdoor Communication Error Multi-system bus failure between header and follower units. Inspect terminal connections between outdoor modules. H01 Compressor Overcurrent What are the current (e