Fault code F4; system may shut down on high discharge temperature.

Safety first: Turn off power at the outdoor disconnect. The discharge line can be extremely hot.

• Step 1 – Locate sensor: Find the small clamp-on or strapped sensor on the compressor discharge line near the compressor.
• Step 2 – Inspect attachment: Ensure the sensor is firmly clamped to the copper line and insulated if originally covered. Re-secure if loose.
• Step 3 – Check wiring: Inspect the sensor wires for cuts or burns. Reseat the connector on the outdoor control board.
• Step 4 – Coil cleaning: Clean the condenser coil and verify outdoor fan operation to reduce discharge temperature.
• Step 5 – Sensor replacement: If the sensor is physically damaged or tests open/shorted with a meter, replace it with the correct Keeprite discharge temperature sensor.
• Step 6 – Board diagnosis: If a new sensor does not clear F4, the outdoor control board may be faulty and should be replaced by a technician.