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.
| Terminal | Label | Connection | |----------|-------|-------------| | 1 | L (Line) | 24V AC Hot (or 110V AC Live) | | 2 | N (Neutral) | 24V AC Common (or Neutral) | | 3 | COM | Common for sensor or relay | | 4 | NO | Normally Open relay output | | 5 | NC | Normally Closed relay output | | 6 | S1 | Temperature sensor 1 (positive) | | 7 | S2 | Temperature sensor 1 (negative) | tgc bc901h manual
If you’ve recently purchased a TGC BC901H device—whether it’s a smart thermostat, a sophisticated battery charger, or an industrial control unit (depending on the product line, as TGC produces varied electronics)—you know that the included printed “quick start” guide often leaves much to be desired. Finding a complete, easy-to-read tgc bc901h manual can be a challenge. A: The backlight may have failed, or display
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). If truly blank, the LCD driver may be faulty
| 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. |