| 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. |
✅ Safely install and wire the device. ✅ Program daily and weekly schedules. ✅ Troubleshoot common errors (E1, E2, E5). ✅ Access advanced parameters for fine-tuning. ✅ Perform maintenance and (if applicable) firmware updates. tgc bc901h manual
A: The backlight may have failed, or display contrast is zero. In the dark, shine a flashlight at an angle. If you see faint numbers, adjust F05. If truly blank, the LCD driver may be faulty. | Error Code | Meaning | Solution |
Remember that while this article mirrors the official manual for most BC901H versions, always defer to the printed safety labels on your specific unit. If you encounter a persistent problem not covered here, reach out to TGC’s technical support with your error code and serial number. | | E3 | Communication error (Modbus) |
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.
A: Use the calibration offset (F04). Check that the unit is not mounted near a draft, window, or heat source.
Save this page, bookmark it, or print it—you never know when you’ll need to troubleshoot your TGC BC901H at 2 AM. This guide is for informational purposes only. The author is not affiliated with TGC Electronics. Always consult a licensed electrician or HVAC technician for installation involving high voltage. Product specifications may change without notice.