ASD Question

DS was recently DX'ed with ASD. He is starting an intensive therapy program next month of 20 hours of therapy per week until he goes to school. Until then I don't really have anyone to ask questions to regarding the little things that come up so I figured this place would be a good place to ask.

Very random, but DS has a huge obsession with heat pumps (those electric heaters that are mounted on a wall near the ceiling). He loves to point and grunt at them (over and over) and will literally try to climb the wall (or anyone or anything near the heat pump) to get closer to it. Even if it is not on, and there is no heat coming out of it. If there is one in the room his attentions is 100% on the heat pump and it is very hard to distract him from it. Don't ask me why, this is just his thing.

At a play group that we go to, DS recently discovered there is 2 heat pumps in the room. It is a very big room with lots of stuff on the walls, so he didn't notice them until just recently even though we've been going to this play group for a while. Now that he knows they are there, it makes going to this play group difficult because he makes such a scene and he literally tries to climb on top of me to get close to them for the entire 2 hours we are there. And if I won't help him get close to the heat pumps he tries to drag one of the other adults over to one of the heat pumps in hopes that he can climb all over them to get to it. He no longer plays with any of the toys, or does the typical things he normally does at play group. He's basically just there to look and point at the heat pumps.

What do I do? I'm almost at the point of not wanting to go to this play group anymore, but I can't just stop going to stuff like this and places that have heat pumps. Besides, as a SAHM, play groups are one of the only ways I get out of the house. Am I suppose to completely ignore this behavior? If so, specifically how do I ignore it when the behavior is so difficult to control? Should I leave when he starts doing this and avoid places with heat pumps in hopes that the obsession will lesson after a lot of time without seeing one? I do plan on discussing this with his therapy workers when therapy starts next month, but in the mean time what do you think I should do?