If the vent fan is only pulling out of the garage and not the attic space then it wouldnt help the attic much which is what you want to cool.
Attic fan direction.
These fans are usually wired to run in one direction.
However the utility of attic ventilation fans is actually quite a controversial topic.
During the summer an attic can be 40 to 50 hotter than the outside temperature which in turn heats up the house very quickly.
One static vent style is the turbine vent which uses wind to power its enclosed fan all it takes is a light breeze to rotate the blades and suck heat out of the attic view example on the home.
Good insulation reduces fan effectiveness.
Quietcool attic fans work almost everywhere almost anytime.
With an attic fan you can cool the attic to the same temperature as it is outside greatly reducing the house from heating as quickly.
Some whole house fans however can be reversed to spin in the opposite direction.
Its thermostat is installed in a control box and is prewired.
The fan is warranted for five years draws a mere 3 2 amps and is capable of handling an attic area up to 1500 sq.
Whole house fans are used to blow hot air out of the attic by sucking cool air through the house up though the whole house fan and out though the gable vents in the attic.