Hi all. 2017 MCS with about 10k miles. Since new I have noticed that the AC works really well on hot and sunny days, but on days like today, mid 70s and cloudy, I have the set it down to like 66 to get cold air to come out. But on 100 degree days, I can set it at 72 and it freezes me out. I generally use AUTO setting with midrange fan speed at 68-72, but again, on a day like today where the outside temp is 75, nothing below a setting of 66 makes a dent in the air temp in the car.

So, at next months oil change, not sure if I should report a problem. I mean, if I want the car freezing, I can hit Max AC and see icicles soon after. But in my other cars, a setting of 70 will freeze you out if the outside temp is above 70.

Does anyone else notice this? I am wondering if the AUTO temp sensors need to see bright sun in order to give me full cooling performance? If so, is that a bug, or a feature?

 

Honestly, my AC temps are "set and forget". I think my side is set to 68 and wife's is 66. Fan speed is set to auto, but will use the recir when we first enter to cool car down. I find that adjusting the air flow rather than temps provides a comfortable compromise. If we get a bit too cool we will knock the fan speed down a notch or two, same if we get too warm. Of course our Florida temps are always 90 or higher, so AC always seems to throw "snowballs" at us. On a 75 degree day, your likely to get just a barely cool flow of air (not cold). The temp differential from AC setting to ambient air temp will affect the coolness of air being delivered IMO.

I'd wager your AC unit is operating as designed.

 

Thanks for the reply. For sure, if its HOT out, like Florida temps, the AC definitely works. Even if I just have it set to AUTO 70 on both sides and midrange fan speed. Its days like today, 75, high humidity, and cloudy, that are more....annoying? Something weird about having to set the temp dials to 66 or lower to get the car to cool down. Maybe it's just a mental thing, lol.

 

Same problem with my 14 F56. I always have to go many degrees in one direction to get heating or cooling to work in similar scenarios to what you describe. I figured that they probably have the thermoprobe/thermostat located in a bad spot.

 

I'm like USA-Ret, I just leave the temp at its lowest and adjust the fan speed. In those rare rare RARE cool mornings in Hawaii I might adjust the temp up a little otherwise I just leave it alone.