Here is a fix that might lower your A/C vent temperatures. When you slide the temperature control selector on the dash between hot and cold, it opens/closes the hot water valve. When the temperature selector is at the full cold position, the hot water valve should be closed. In my case the valve was still partially open, which introduced hot water into the heater core. After making an easy adjustment to the control cable, I saw my vent temperatures drop 2-3 degrees, which was welcome in 110 degree Phoenix heat. I've seen other posts on this issue, so I suspect others might have this problem as well. The hot water valve is mounted dead center on the firewall with heater hoses coming off each side. You can easily see how the control cable pushes/pulls on the valve handle to close/open it. With the engine running and the temperature control selector on full cold, make sure the valve handle bottoms out against the stop. If there is any gap, you need to loosen the cable housing clamp and re-position the cable until the valve closes completely. The drawings below should clarify how it all works.