Easily! Depending on the car, the color, the location, etc, the interior can easily surpass 150 Deg F on a day where the ambient is in the 90's. The default, failsafe for mobile HVAC systems is for the fresh/recirc door or flap to go to fresh air. So, unless, for some unintelligible reason, the manufacturer would activate the fresh air/recirc door to "recirc" for parking fan activation, pulling in 90-95 deg ambient air to push 150 deg cabin air out the relief vents in the back would easily result in a 20-30 deg F reduction in cabin temp, if active for say, 60 min or more. Better if constantly active whilst parked.