I once read (or heard) that you should turn your AC off every time you turn your vehicle off. It is supposed to be easier on you system than just leaving it on when you shut off your engine.

Is there any truth to this or is it just a bunch of crap?

 

I personally don't think it really makes a big enough difference to lose sleep about. The A/C compressor clutch does take a fair amount of electrical grunt to get going, so I guess in extremes it would be wise to turn the A/C off before killing the engine. I think it matters more because with the A/C on, when the engine is cranked sometimes the system will make weird noises on startup from the refrigerant swooshing around in the lines. I've had a few people complain about that before.

I turn mine off everytime I kill the engine.

 

An old mechanic friend of the family used to tell us to turn it off, but if you read the owners book, it says turn air off only when used on Max A/C, reg a/c was no biggy. It also says to shut defrost off in snowy conditions. I turn mine off 9 times out of 10, just a habit.

 

I turn mine off when I am putting the truck away for a few hours or the day. What I do is press the AC button, and kick the fan up on high, running the system, taking in outside air.
I do this to try to prevent any mildew from being created, but it is a SOTP type process, I have no foundation in reality for doing this, just something I do to feel better about my truck

The only hard and fast rule from the OM is to not leave the setting on MAX AC or off ( think that is the other setting ) as these have the system in recirculate mode, and no fresh air can get into the system. Think that is for the same reason as my process ??

Nothing about starting the engine with the AC ( normal ) on in the OM.