Can you tell me about these?

[Mtrdrms]

So, I just picked up a bus and I know nothing about these AC units. I'm hoping you can help. They are dometic but that's all I know. They say there is "optional heat" but how do I know if they have that option?
My bus has 2 of these and only one will turn on but it sure doesn't blow heat. Any information on these would be appreciated. Thanks!