I've found this works pretty well, but the best way of keeping the a/c odour free is to never switch it off.
Nothing wrong with leaving it on Auto, it seems to work well, just make sure a/c is on, too.
Yes, I had that brief smell with my 500 but never got around to doing anything.
Your car is a US model, which may behave differently. If I switch off the ac on mine, the Auto light goes off. If I push the Auto button, it goes back to Auto mode and ac comes back on again! Strange.
It depends on what temp you have set ,my air con works on auto at all temps. If temp is quite high on auto the ac will switch off when auto is pressed.
In my case temps don't matter, AC always turns auto off.
So your AC only works on manual mode?
So, basically, when I switch the AC on, it annuls the auto mode to give me the full control. Otherwise, the system decides whether the AC should be working or not, based on the set temperature. The fact that the AC light is always off in the auto mode doesn't necessarily mean it's not working.
Recommended setting for CC is auto all the time.
I have mentioned in other threads I did have to have my AC regassed when we bought it as it had been stood for a bit but the system generally in the 500X seems to work very well - i.e. It gets damn cold!