idling with AC on

Jul 27, 2005 6 Replies

I used to think idling (maybe more than 5 min) was bad for engine, but then I read elsewhere that it's no worse than driving. I think i read that idling with AC on puts alot of stress on the engine. Is this true? Should I turn off the AC if idling for more than 5 minutes? I have a dodge truck, and ideally I could sit in it for 15 minures, idling, with AC on...



Also, in the winter, is idling with heat on any problem?



It's interesting that in older non-computerized cars, the A/C would *lower* the idle rpm, thus conceivably *saving* gas at idle! In newer cars, the A/C bumps up the idle speed, indeed costing more gas. 'pyooters, donchaknow....

Idling in winter w/ the heaters on can conceivably lower engine temp. Ackshooly does help if the engine is *over*heating.

What gets me is the new thing of driving off w/o warming up the car at all, as per, sposedly, mfr's instructions!

This is not necessarily true. On my car, turning the A/C on while idling forces one of the engine fans on, keeping the engine cooler.

When I lived in West Texas the company bought me a brand new Chevy 4dr truck. We (me & crew) used to leave the truck running in the summer for the A/C and in the winter for the heat. The engine lasted 9 months before it wore out. The next guy that got it had it for 1 year before it needed a new engine.

Police all over the country do the same thing and their engines don't wear out in a year. Sounds like that truck had a problem but it had nothing to do with letting it idle with the AC or heater on.

"mac" writes in article dated 27 Jul 2005

09:11:58 -0700:

Idling with the AC on puts stress on the AC due to reduced airflow over the condenser, causing higher temperature and pressure and more work for the compressor. Especially if your engine fan is belt-driven (so it runs slower at low engine RPM).

The engine itself should handle it fine.

No, not any worse than driving.

-- spud_demon -at- thundermaker.net The above may not (yet) represent the opinions of my employer.

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