I don't know which models exactly but Honda uses a sensor on the AC unit that reads RPM. Then matches that with engine RPM. If it senses a difference, to keep from burning up belts, it will cease function of the Compressor clutch. I think this only applies if the AC compressor shares a belt with the alternator. And, I believe the red light is the indicator that this is happening. I can't recall for sure though, anyone else have input?