Unit shows E3 and stops cooling; compressor may not start or may shut off quickly.

Safety: Unplug the air conditioner. If it is a window unit, be careful not to disturb its mounting when removing covers.

Steps:

• 1. Confirm error: Clear power for 5 minutes, restore power, and check if E3 returns.
• 2. Access condenser section: Remove the outer cabinet or rear cover to access the condenser coil (the warm coil at the back). On some Frigidaire models, the outdoor sensor is clipped to the condenser coil or mounted near the exhaust area.
• 3. Locate sensor: Find the small probe or clip-on sensor with two wires leading to the control board. Note its routing.
• 4. Inspect and reseat: Check for broken wires, rodent damage, or corrosion. Reseat the connector at the board.
• 5. Test resistance: With the sensor unplugged, measure resistance and compare to spec. If open/shorted or far off spec, replace.
• 6. Replace sensor: Install a compatible Frigidaire outdoor temperature sensor. Clip it securely to the same location, away from fan blades.
• 7. Check board: If the sensor tests good and E3 persists, the main control board may be faulty and require replacement.

Note: Accessing the condenser section may require removing the entire chassis from the window sleeve. If this is beyond your comfort level, contact a technician.