Goodman ductless mini-split or packaged AC displays E1 and stops cooling

Safety first: Shut off power to both indoor and outdoor units at the breaker and outdoor disconnect. Confirm power is off before touching wiring.

Steps to check:

• 1. Verify wiring diagram: Remove the front cover of the indoor unit and the service panel on the outdoor unit. Locate the Goodman wiring diagram on the panel and confirm which terminals (e.g., 1-2-3 or S1-S2-S3) should be connected.
• 2. Check terminal tightness: At both indoor and outdoor units, gently tug each conductor at the communication terminals. Tighten any loose screws and ensure no copper is exposed that could short to the cabinet.
• 3. Confirm polarity: Make sure wire 1 goes to 1, 2 to 2, 3 to 3 (or S1 to S1, etc.) between indoor and outdoor. Reversed conductors can cause E1.
• 4. Inspect cable condition: Trace the communication cable between units. Look for UV damage, cuts, or splices. Replace damaged cable with appropriately rated multi-conductor cable.
• 5. Power reset: After corrections, restore power and wait 5–10 minutes for the system to re-establish communication. Check if E1 clears.

When to call a professional: If wiring is correct and E1 persists, a failed indoor or outdoor PCB is likely. Board replacement and system re-commissioning should be done by a licensed HVAC technician.