Unit stops cooling and displays E1 on the control panel; fan may still run but compressor cycles off quickly.

Safety first: Unplug the Hotpoint air conditioner from the wall outlet before removing any covers. Capacitors can hold a charge; avoid touching exposed terminals.

Steps to check and correct:

• Power reset: Disconnect power for 5 minutes, then plug back in and try again. If E1 returns, continue.
• Locate the ambient sensor: Remove the front grille and filter. Behind the grille, near the air intake or evaporator coil, look for a small probe-style sensor (often wrapped in plastic or clipped to the coil) with two thin wires leading to the control board.
• Inspect wiring: Check for broken, pinched, or corroded wires and loose connectors. Reseat the plug on the main PCB by unplugging and firmly reconnecting it.
• Check sensor resistance (if you have a multimeter): With power still disconnected, unplug the thermistor from the board and measure resistance across the two leads. At room temperature (around 25°C / 77°F), most Hotpoint NTC sensors read roughly 5–20 kΩ. A reading of 0 Ω (short) or OL (open) indicates a bad sensor.
• Replace if faulty: If the sensor is open/shorted or physically damaged, replace it with a compatible Hotpoint ambient thermistor. Route the new sensor wiring along the original path and secure it away from the fan blades.
• Reassemble and test: Refit the grille and filter, restore power, and run the unit in COOL mode to confirm the E1 code is cleared.

When to call a technician: If the sensor tests good but E1 persists, the main control PCB may be defective and should be diagnosed or replaced by a qualified technician.