A: Use the calibration offset (F04). Check that the unit is not mounted near a draft, window, or heat source.
| Error Code | Meaning | Solution | |------------|---------|----------| | | Room sensor open or shorted | Check sensor wires at terminals S1/S2. Replace sensor if resistance is infinite or zero. | | E2 | Evaporator/External sensor fault | Same as E1, but for second sensor. | | E3 | Communication error (Modbus) | Check RS485 wiring; ensure baud rate matches master device. | | E4 | Power supply under-voltage | Below 18V AC. Check transformer or power supply. | | E5 | Relay stuck or welded | Internal fault. Cycle power. If persists, replace unit. | | EE | EEPROM failure | Factory defect – contact TGC support for replacement. | | LO | Temperature below range (< -40°F) | Sensor may be disconnected or environment too cold. | | HI | Temperature above range (> 248°F) | Sensor shorted or exposed to extreme heat. | tgc bc901h manual
Refer to the wiring diagram inside the terminal cover. Below is a standard mapping: A: Use the calibration offset (F04)
To change: Use ▲/▼ to select parameter, press , adjust value, press SET to store. Exit by pressing MENU repeatedly. ⚠️ Changing F01 (differential) to too low a value can short-cycle your compressor. TGC recommends keeping it at 1°F for residential HVAC. Section 6: Troubleshooting Common Error Codes (TGC BC901H) When something goes wrong, the unit displays a code. Here’s what they mean, per the manual. Replace sensor if resistance is infinite or zero
A: Yes, if your model has an O/B terminal for reversing valve. Set parameter F10 (not shown in basic menu) to 1 for O terminal (cooling active) or 2 for B terminal (heating active).