A big ole...depends.
How much space and airflow is there in the attic area?
A ventilation fan would certainly help but again without details of the space hard to say if it will be enough.
If its a small poorly ventilated space, temps could easily push 130F in the attic. On really hot days it can go even higher. The Air/con unit at best will be severely hampered in it's cooling ability in those conditions. Plus it will be pumping more heat into that space. You could easily push it up north of 150F.
Those kinds of temps could be really hard on the air/con unit.
PS: Did an experiment several years back looking at LED traffic signals. We put a temperature probe inside the head in direct sunlight. It got up to 160F and the LED unit generates almost no heat. Black shingles would be far worse than a yellow housing for absorbing heat.
