I frequently use the precondition cycle to run the AC in summer when my 2017 Volt has been sitting in my hot garage or baking in the sun. The only issue I have with the climate control selecting the defrost vents is that I get condensation on the outside of the windshield when the humidity level is high and the windshield cools enough to condense the moisture on the outside of the glass. One or two passes of the wiper blades will clear the condensation. When parked outside, I have never had a problem with the Volt not cooling down sufficiently as long as I let it run for at least 8 minutes of the full 10 minute precondition cycle. I do use a sunshade when parked outside. My windows are not tinted other than the factory tint. Inside my garage [Updated] I have timed this now, 4 minutes of AC running will cool down the Volt's interior when set to Auto, Max AC, 70F, recirculate Off. The AC compressor and fan initially ran at a high speed for about 3 minutes, then throttled down to a medium speed. This test was run earlier this evening when my garage was a very warm 94.5 F, this was down from measured daytime high temperature inside the garage of 99 F. Even though my Volt was slow cooking inside my garage all day while it was plugged in I did not notice the Volt turn on the fan or AC compressor to cool the battery during the day. The mass of the battery, ~ 450 lbs as I recall, takes a long time to reach the set temperature point that will cause the Volt to start the battery cooling cycle. It does happen but not as often as I would have expected, usually happens when I am charging at home and the garage temperature is above 90 F. I did not remember to check the engine coolant temperature when I was still inside my garage but about a half mile from home the coolant temperature display read 100 F. I realize that the engine coolant and the battery coolant are on different cooling loops, I was only trying to determine the temperature of the Volt's systems prior to running the preconditioning cycle. Perhaps the battery coolant temperature was significantly lower than 100 F prior to the preconditioning, the Volt does not provide this information via the normal Driver Information Display.