Indoor wall control / thermostat displays E1 and the air conditioner will not respond to temperature changes or mode selections.

Safety first: Turn off power to both the indoor air handler/furnace and the outdoor Keeprite condenser at the breaker and service disconnect before touching any wiring.

• Step 1 – Power reset: Turn off both breakers (indoor and outdoor) for 5 minutes, then restore power. Check if the E1 code clears.
• Step 2 – Inspect thermostat cable: Remove the thermostat/wall control cover and verify the low-voltage wires are firmly attached and not pinched or damaged. Tighten any loose terminal screws.
• Step 3 – Check communication wiring: At the indoor unit control board, locate the communication terminals (often marked C, R, Y, Y2, COM, or specific data terminals). Verify the same color wires land on the same terminals at the outdoor unit control board. Look for broken, chewed, or corroded wires and repair or replace as needed.
• Step 4 – Inspect control boards: With power off, visually inspect the indoor and outdoor control boards for burnt spots, swollen components, or corrosion. If damage is visible, the board likely needs replacement.
• Step 5 – If E1 persists: If wiring continuity is good and connections are correct, the fault is likely a failed indoor or outdoor control board. At this point, contact a qualified Keeprite technician to test the communication circuit and replace the defective board.