The older Mirage's had a different heater assembly.
Air passing through the heater assy was heated at least 5°C over outside temperature, regardless of the heat being turned off. The flap covering the core inside the heater box was fully closed and yet the car was always being heated.
Newer Mirage's, dunno since when, have a modified heater flap, presumably because of that.
There are basically two sort of designs in cars. First type has a " hot water tap" regulating hot water going through the heater core, but this is not on our cars. Second way to do it is by an air-flap over the heater core, the core itself always being heated, just as in our cars.
Since my 2014 model has the old unmodified kind of flap inside the heater assembly, which heats even in summer, I disconnected the heater core from circulating coolant by means of a "U"-shaped piece of pipe. Coming winter it will be reconnected in order to re-enable heating.
A word of warning: Do not simply block it off, because the coolant must continue to circulate through the throttle body and other parts for example.