Room air Amana window or PTAC air conditioner will not run; display shows E1 and unit may beep once when buttons are pressed.

Safety first: Unplug the air conditioner or switch off the dedicated breaker before removing any covers. Capacitors can hold a charge; avoid touching exposed terminals.

Steps to check and address E1 (room thermistor):

• Power reset: Disconnect power for 5 minutes, then restore. If E1 clears temporarily and returns, continue with diagnosis.
• Access the control compartment: Remove the front grille. On PTAC and window units, remove the screws securing the control panel cover to expose the control board and sensor wiring.
• Locate the room thermistor: It is usually a small bead or bullet-style sensor on two thin wires, positioned near the return air intake or behind the front grille, plugged into the main control board.
• Inspect wiring: Check for broken, pinched, or disconnected wires between the thermistor and the control board. Reseat the connector firmly.
• Test the thermistor: With power still disconnected, unplug the thermistor from the board and measure resistance with a multimeter. At about 77°F (25°C), most Amana NTC thermistors read roughly 10kΩ (check your tech sheet for exact spec). If the reading is open (OL), near 0Ω, or far outside spec, the thermistor is bad.
• Replace if defective: Install a new OEM Amana room thermistor, route the leads away from sharp metal and moving parts, and secure it in the original sensing location.
• If thermistor tests good: The sensor circuit on the main control board may be faulty. Inspect the board for burnt spots or corrosion and replace the control board if needed.

If you are not comfortable using a multimeter or working around electrical components, contact a qualified HVAC technician.