- Use a smaller mix chamber that is rated for the unit in use. If recirculating, decrease flow or decrease temperature setpoint.
- Swap A and B heater output cables and RTD cables and see if issue follows. If so, replace RTD.
- Check for loose heater element wires or loose green connector at TCM.
- Confirm resistance of heater. Heater resistance should be 23-26 Ω. If out of tolerance, replace heater element.