The Canadian rule of 12 fixtures per circuit applies to lighting and
general purpose circuits only. If you have a circuit with 11
fixtures/outlets, you can add one additional fixture or outlet. That
doesn't necessarily mean that you should be plugging an air
conditioner into that outlet.

I believe the CEC states that a wall A/C should be on a dedicated
circuit. Of course if it's an existing home, you could plug it into
any circuit. I'd make sure you don't have any hydro-hungry appliances
like fridge/microwave on the circuit, and I wouldn't be plugging any
hair dryers into the same circuit.

Mr Fixit eh! from Belleville