AC Communication Error — Indoor/Outdoor Signal Failure (E-code)

Check wiring, shield ground, termination resistor

Check: Wire break = check continuity end-to-end (<5 Ω). VDC pulse comm = measure terminal signal voltage (pulses, 1–10V). Shield ground = single end only (both ends = ground loop). VRF/BS box = verify termination resistor ON (DIP switch). Parallel routing with power cables = EMI.

What to do: Wire break = new cable (14/4 stranded, 300V). Shield grounded at one point. EMI mitigation = separate conduit from power (≥100 mm spacing) or add ferrite cores. VRF multi-zone = verify comm topology (daisy chain vs star). Set termination resistor at correct location.