What temperature were you hoping for? 59 degrees is better than fine. I don't know anyone who would be comfortable at that temperature.
There is a temperature sensor on the evaporator in the dash that prevents its temperature from going much below 40 degrees. The humidity in the air condenses on that cold evaporator, then drains out onto the ground by the right front tire. That's what you see dripping when the AC is running. If the evaporator were allowed to get to 32 degrees, that water would freeze into a block of ice and block air flow. You'd get just a little uncooled air.
Now you're taking air that is 90 degrees and blowing it through something that is around 40 degrees. There is WAY more volume of hot air coming in than there is volume of cold refrigerant going through the evaporator, so it's very unusual for the air from the vents be be way down to 59 degrees. In fact, any instructor will tell you the goal of any automotive AC system is to lower the air temperature by 20 degrees. That means your system would be acceptable if the vent temperature was 70 degrees. The comfort comes from removing that humidity, not from lowering the temperature.
The vent temperature will be lowest a little while after switching to the lowest fan speed. That's because there's less volume of hot air coming in trying to warm up the evaporator. What you really need to be concerned with is a vent temperature that's too low. If the water freezes on the evaporator, the cooling will stop. This typically happens after driving at highway speed for an hour or two, and is almost always caused by a defective or mispositioned temperature sensor on the evaporator.
Monday, June 22nd, 2015 AT 11:44 PM