Unit will not run, display shows E1 shortly after power-up or when trying to start cooling.

Safety first: Turn the air conditioner OFF and disconnect power at the wall outlet or breaker before removing any covers. Capacitors inside the unit can hold a charge; avoid touching any exposed terminals.

Steps to check and correct:

• Power reset: Unplug the unit or switch off the breaker for 5 minutes, then restore power and see if E1 clears. If it returns, continue.
• Access the front panel: Remove the front grille and filter to access the control area on a window or wall unit. On split systems, remove the indoor fascia panel as per the user manual.
• Locate the room temperature sensor: It is usually a small thermistor probe near the air intake or behind the front grille, connected by two thin wires to the indoor control PCB.
• Inspect wiring: Check for broken, pinched, or disconnected wires and loose plugs at the PCB. Reseat the connector firmly.
• Test the sensor: Using a multimeter set to resistance (ohms), measure the sensor at room temperature. Compare the reading to the Westinghouse service chart for the specific model (typically 5–20 kΩ at 25°C). If it reads open (infinite) or near 0 Ω, the sensor is defective.
• Replace if faulty: If the thermistor is out of spec, replace it with the correct Westinghouse room temperature sensor for your model. Route the new sensor in the same position and secure it away from the evaporator coil fins.
• Check the PCB: If a known-good sensor still gives E1, the indoor control PCB thermistor circuit may be defective and will need replacement by a qualified technician.

When to call a professional: If you are not comfortable using a multimeter or removing the indoor cover, or if the PCB appears damaged (burn marks, corrosion), contact an authorized Westinghouse service technician.