Problem with bees or wasps?

Bees (or wasps) have invaded an old, unused air conditioner at my house. I have tried emptying cans of bee/wasp spray into the side where they bees have been entering and exiting, but I suspect that I’m not really getting them because the nest is deep within.

Here is a photo. The red square shows where they are entering/exiting.

Does anyone have a suggestion? The air conditioner is loud with the buzz of what sounds like a million bees. There are often 30 or so bees just going in and out. I think this is a huge nest. I have young children, so I need to take care of this soon. Plus, I have a guy coming to remove the air conditioner and put in a larger window soon. He won’t touch bees.

I was considering putting an old towel over that side (tonight when they are less active), then drenching it with bee spray. I’m stumped.