July 5, 2004

12:37 PM

Is it bad for a car's air conditioner to leave it running while idling for 15 minutes or so? Does the fan setting matter? Also, is it bad to have the a/c going hard while driving around in the heat everyday?
posted by callmejay to (9 comments total)

I hate to be hot, so I use the a/c pretty hard. I've had a couple of cars now where it's stopped working for various reasons. I'm just wondering if it's something specific I'm doing.
posted by callmejay at 12:39 PM on July 5, 2004

Well, the more you run it, the more pressure is put on the system and the more likely you are to have a refrigerant leak, but they tend to all leak eventually anyway.
posted by kindall at 12:49 PM on July 5, 2004

Don't worry, run me all you want. I won't leak, promise.
posted by ac at 1:13 PM on July 5, 2004

BTW, I also ***HATE*** to be hot... people call me a cry baby about it, but then I burst into tears and it shuts them up.
posted by ac at 1:14 PM on July 5, 2004

1. No, it's just wear on the components. Idling is "worse" for the system because the condenser (the part that sheds heat) doesn't cool as well, thereby increasing the duty cycle of the compressor (the moving part of your system).

2. Yes. Higher fan settings will drive more air over the evaporator, making it less cool, thereby increasing the duty cycle of the compressor (the moving part of your system).

3. For the reasons mentioned in (1.), driving around (moving, rather than idling) is actually the least demanding for the compressor. Increased airflow over the condenser cools the refrigerant best, leaving the compressor with less "work" to perform.
posted by trharlan at 1:46 PM on July 5, 2004

If you care about other people, it makes the air around your car hotter, which is worse for cyclists, pedestrians, etc. Sometimes this makes evil cyclists kick your car, especially if you've left it idling, so yeah, it could be bad for it, depending on where you live and how many angry cyclists there are.
posted by dame at 5:09 PM on July 5, 2004

Actually, you can damage your a/c unit. I know from personal experience.

On a hot NJ day about a decade ago, I ran my Mitsubishi's a/c while the car was idling to cool the car off. Probably about 5-10 minutes of idling. The a/c all of a sudden burst under the pressure -- specifically, a seal had broken under the strain. The cabin was filled with what I thought was smoke from an engine fire, which turned out to be (relatively) harmless refrigeration coolant spewing from the vents.

When the car is in motion, the heat is dissapated relatively quickly. When you're idling, you'll usually hear the engine fan kick in quickly because -- surprise -- it's too hot for the system to handle and puts an enormous amount of strain on it.
posted by Civil_Disobedient at 7:09 PM on July 5, 2004

None of this should dissuade you from operating the A/C, callmejay. Unless you're idling all the time, your usage of the A/C likely falls within normal limits. Certain models clearly have higher-than-average A/C failure due to lousy parts or even design.

But on any car, there's plenty of stuff that can break or fail at random. Some systems are more fragile than others under heavy use; the A/C system is one of the weakest, generally. It is the number one reason taxis have to taken out of service at my garage during the summer months in NYC.

So that's a qualified 'yes' on all 3 questions, I guess. Use the A/C a lot, well, something goes buck-wild sooner rather than later. It'd be helpful if you described the various problems...I mean, the A/C broke on a 2-month-old taxi I was driving once. It was just a busted switch somewhere; no big deal. That can happen too.
posted by attackthetaxi at 8:00 PM on July 5, 2004

Like anything mechanical, the more you use it, the sooner it will wear out. Other than that, you cannot really damage something by using it.
posted by dg at 9:05 PM on July 5, 2004