Keeprite unit shows F5; system may not start or may shut down intermittently.

Safety first: Turn off power at the outdoor disconnect before opening the control panel.

• Step 1 – Locate sensor: The outdoor ambient sensor is usually mounted near the condenser coil or in the control compartment, exposed to outdoor air.
• Step 2 – Inspect sensor and wiring: Look for cracked sensor housing, chewed wires, or corrosion. Repair or replace damaged wiring.
• Step 3 – Reseat connector: Disconnect and reconnect the sensor plug on the control board to ensure a solid connection.
• Step 4 – Test sensor: With power off, measure resistance and compare to Keeprite ambient sensor chart. Replace if out of range.
• Step 5 – Replace sensor: Install the correct Keeprite ambient temperature sensor, mount it in the original location away from direct sunlight and hot exhaust, and secure wiring.