AC on full blast in Canada?!? Bet you are glad that you don’t live in Florida. Just kidding as I know that you can see 100°+ days just like we do.
Most likely, what is happening is that at idle, w/ the AC on, the rpm is dropping just enough to cause the motor to shake. Not much of a drop in rpm is required. To verify, look at the rpm with the AC off as well as with it on. Try bringing up the rpm a bit and the shake should go away.
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