I also run one no matter the time of year and it consistently is removing moisture from the air. I cannot answer with any level of conviction your question about A/C... But it did make me wonder... I commented on another thread about Greyhawk's weak A/C that mine seemed to perform better then was being reported by many other members. Makes me wonder if the dehumidifier is making a difference.
Of course the only way to test it would to be trying camping without the dehumidifier, and I am not about to do that