Furnace shows E7; inducer and blower may run unexpectedly or not at all; thermostat appears unresponsive.

Safety: Turn off furnace power before touching low-voltage wiring.

Steps:

• Remove the furnace access panel and locate the low-voltage terminal strip (R, C, W, Y, G) on the Westinghouse control board.
• Verify that the thermostat wires are firmly attached and not frayed or touching each other.
• At the thermostat, remove the cover and check that the same color wires are connected to matching terminals.
• To test the furnace, with power OFF, temporarily disconnect the thermostat wires at the furnace and then, with power ON, jumper R to W at the control board. If the furnace starts normally, the thermostat or thermostat cable is likely faulty.
• If E7 persists even with a jumper, the IFC may have a failed thermostat input circuit.

Warning: Only jumper low-voltage terminals; never jumper high-voltage connections.