Boiler display shows A23; unit may lock out or operate erratically.

Safety: Turn OFF power before working on wiring.

Steps:

• 1. Locate outdoor sensor: Find the Raypak outdoor sensor mounted on an exterior wall, away from direct sun or exhaust vents.
• 2. Inspect cable: Follow the cable back to the boiler. Look for cuts, staples through the wire, or water intrusion at junction boxes.
• 3. Check connections: At the control board, ensure the outdoor sensor wires are firmly attached to the correct terminals and not shorted together.
• 4. Compare temperature: Compare the displayed outdoor temperature to actual outdoor conditions. If the reading is extreme or unrealistic, the sensor is likely bad.

Replace the outdoor sensor if defective. If A23 remains, verify control settings for outdoor reset are correct or have a technician evaluate the control board.