Portable or window Soleus Air AC will not run; display shows E1 and unit may beep repeatedly.

Safety first: Unplug the air conditioner from the wall outlet before removing any covers. Capacitors inside can hold a charge; do not touch bare terminals.

• Power reset: Unplug the unit for 5 minutes, then plug back in and try again. Sometimes E1 can be a transient sensor reading error.
• Access the front panel: Remove the front grille or filter cover on your Soleus Air unit. On many Soleus portable and window models, the room thermistor is clipped near the evaporator coil or behind the air intake grille.
• Inspect the thermistor: Look for a small probe with two thin wires going to the control board. Check for broken insulation, corrosion, or a sensor that has fallen out of its clip and is dangling.
• Check connections: Follow the thermistor wires to the main PCB. Reseat the plug by unplugging and firmly reconnecting it. Ensure there are no bent pins or burnt spots on the board.
• Test the sensor (if you have a meter): With the unit unplugged, disconnect the thermistor and measure resistance. Compare to the Soleus Air service chart for your model (typically 5–50 kΩ depending on temperature). A reading of 0 Ω (short) or infinite (open) indicates a bad sensor.
• Replace if faulty: If the thermistor is open/shorted or physically damaged, replace it with a Soleus Air-compatible room temperature sensor for your exact model. Route the new sensor in the same location and secure it with the original clip.
• Reassemble and test: Reinstall covers, plug the unit back in, and power on. The E1 code should clear automatically if the sensor is functioning.