Furnace shows E14, no heating, may occur after thermostat or control wiring changes.

Safety: Turn off power before working on control wiring.

Steps:

• Verify wiring: Check the low-voltage terminals on the Cointra furnace and the room thermostat. Ensure wires are connected to the correct terminals as per the installation manual.
• Inspect cable: Look for damage to the thermostat cable, especially where it passes through walls or near sharp edges.
• Test with a simple thermostat: If possible, temporarily connect a basic on/off thermostat or a Cointra-compatible controller to rule out an incompatible device.

Professional help: If wiring and thermostat are correct, the control board communication circuit may be faulty and should be tested and replaced by a technician.