Payne split system shows E5; outdoor unit may not start or may shut down quickly after start.

Safety: Turn off power to both indoor and outdoor units before touching any wiring. Low-voltage circuits can still short and damage boards.

• 1. Power cycle: Turn OFF the furnace/air handler breaker and the outdoor condenser disconnect for 5 minutes. Turn them back ON and set the thermostat to COOL. If E5 clears, it may have been a transient fault.
• 2. Inspect thermostat/control cable: At the outdoor unit, remove the control panel cover. Check the low-voltage wires (typically R, C, Y, etc.) for loose connections, corrosion, or rodent damage. Tighten terminal screws and repair any damaged sections.
• 3. Verify polarity and connections: Ensure that the same color wires are connected to the same terminals at both the indoor and outdoor control boards (e.g., Y to Y, C to C). Miswiring can cause communication errors.
• 4. Look for water damage: Inspect the indoor control board for signs of water intrusion from a clogged condensate drain. If the board is corroded or burned, it will likely need replacement.
• 5. Call a technician if unresolved: If wiring is intact and E5 persists, a professional should test the 24V transformer, communication circuits, and replace the faulty control board if necessary.