HEAT Annunciator ON, Relay Pack LED IS LIT - Supplemental heat equipment not energized

What does HEAT Annunciator ON, LED IS LIT mean?

The slave thermostat's 'HEAT' annunciator is on, and the LED on the HR-03 relay pack is also lit, indicating that the relay pack is receiving a signal. However, the corresponding supplemental heating equipment stage is not energized. This points to a problem between the relay pack and the heating equipment, or an issue with the equipment itself.

• Missing 24 VAC power to the HR-03 relay board.
• Wiring error between the relay pack and the equipment.
• Faulty HR-03 relay board (e.g., bad relay).
• Problem with the contactor coil or the contactor itself.
• Defective heating equipment or no power to the unit.

Click steps to track your progress.

1. 1

   Check the AC voltage across the HR-03 relay board common (red) and any deenergized relay output (e.g., H2 or H3/FAN); it should read 24 VAC. If not, check for wiring errors.

2. 2

   Check the AC voltage across the HR-03 relay board common (red) and the suspect relay board output (e.g., H1); it should read near zero (less than 1 VAC). If not, suspect a bad relay board.

3. 3

   Check the AC voltage across the suspected contactor coil; it should read 24 VAC. If not, inspect the contactor coil wiring for faults.

4. 4

   If voltages are correct, investigate other possibilities such as a bad contactor, defective heating equipment, or a complete lack of power to the heating unit.