RE: Arctic Air Air Conditioning
I've an older Hydronics system on my boat. While we have the Heat/Cool selector switch, we've learned you need to let the compressors run for awhile in heat mode before turning on the individual zone units. Also, each zone should run at the lowest fan setting to get the best heating performance. Surprisingly enough, running at low fan settings heats the livings spaces relatively quickly.
It's not an Arctic Air unit, but you might try running the heat this way and see if it kicks in.