Starting cars with the A/C on or off position??

[Guest987]

I wanted to get opinion on starting car with AC in on or off position. Does it need to be off or does it matter anymore. I know years ago they didn't promote to have it in the on mode.

[whunter]

All newer cars 1981 + are supposed to be able to handle it with NO issue.

If the engine and/or cooling system has problems, it may be desirable to stop using the A/C until repairs are done.

What year and model are you asking about?


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[Guest987]

I wasn't referring to any model or year specific, but just checking to see if the old adage still was in effect or not?

[Air&Road]

The reason Roy wants to know the year and model is because some MB's have a delay so that the engine has time to start, stabilize and build oil pressure before engaging the compressor. If it is a car that does NOT have this feature, then yes you should wait 5 seconds or so after starting the engine to allow oil pressure to come up before loading the front main bearing with the compressor load.

[Peter Guenther]

Originally Posted by Air&Road

The reason Roy wants to know the year and model is because some MB's have a delay so that the engine has time to start, stabilize and build oil pressure before engaging the compressor. If it is a car that does NOT have this feature, then yes you should wait 5 seconds or so after starting the engine to allow oil pressure to come up before loading the front main bearing with the compressor load.

The compressor usually does not put a immediate load on the engine since it has to build pressure first

[Guest987]

I still try to not have it in the on position on all my vehicles. With such torrid weather around, I am just kind of the opinion not to put any undue stress cranking, if I can avoid it. Sometimes I forget!

[Air&Road]

Originally Posted by Peter Guenther

The compressor usually does not put a immediate load on the engine since it has to build pressure first

Don't tell me, tell the MB engineers. They are the ones that engineered in the five second delay, at least on the 124 cars.