My air conditioner sometimes smells like antifreeze and my mechanic did a pressure test to confirm that it wasn't a coolant leak The AC works okay could it be freon?

Try turning the switch to recirculated air or max cool. When you put the switch on just A/C and not max the blower pulls in some fresh air which may be coming from under the hood. The smell could be coming from a heater coil if the heat valve is not shutting off all the way. Or the car could be running a little hot when the A/C is on. But the antifreeze smell is not freon. The 2 are distinctively differant and probably not being confused.