Furnace inducer motor runs but burners do not light; E3 code on control board

Safety: Turn off power to the furnace. Do not operate the furnace with venting disconnected except for brief testing by a professional.

• 1. Inspect vent and intake: From outside, check the PVC exhaust and intake terminations for leaves, snow, bird nests, or debris. Clear any obstructions.
• 2. Check condensate drain: On high-efficiency Frigidaire furnaces, verify the condensate trap and hoses are not clogged or kinked. Flush the trap with warm water and reassemble.
• 3. Inspect pressure switch tubing: Remove the front panel. Locate the pressure switch and its rubber tubing to the inducer or collector box. Ensure tubing is not cracked, loose, or filled with water. Replace damaged tubing and clear any moisture.
• 4. Test pressure switch operation (basic): With power off, gently blow through the tubing to ensure it is clear. Do not suck or blow hard into the switch itself. If the switch rattles or feels stuck, it may be defective.
• 5. Inducer check: Restore power and call for heat. Confirm the inducer motor starts promptly and runs smoothly without loud grinding. Weak or noisy operation suggests a failing inducer assembly.
• 6. Professional service: If E3 persists after clearing venting and tubing, have a technician measure inducer draft and pressure switch operation with a manometer and replace the pressure switch or inducer motor as needed.