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Napping in car

I work with someone who, because of health problems, often leaves the office and sleeps in her car, parked in an unenclosed parking garage, with the motor running and air conditioning on, for an hour or 2. Is this safe?

it’s unenclosed, so assuming there aren’t any rust holes in the wrong place, it shouldn’t cause her physical harm. It’s not overly great for the car, however. At minimum she’ll probably be replacing exhaust components more often than usual.

I don’t think it is any less safe than sleeping in an idling tractor trailer (or one with a running generator), and truckers do it every night across the USA, as do thousands of RV owners with their generators.

It isn’t very good for the engine, or air quality. Perhaps her boss should accommodate her health issues and make a place for her to sleep inside the building.

As long as the car is in good shape it not only is safe but won’t hurt the car.

Idling old carburated cars for long periods used to be bad for the engines bacsue the old carbs ran rich and if idled for long periods carbon deposits could build up in the cylinders. Carbon can foul sparkplugs, and it retains heat which could lead to hot spots and preignition when the engine was again put under load. Old engines were also subject to dilution of the oil from excess gas, but for the sake of brevity I’ll dispense with a dissertation. Modern cars do not have this problem. They run far leaner and aerate the gas far better, leading to far cleaner operation and no significant deposits.

Engines also create water vapor as they run. Until the exhaust system is warmed up, that vapor can condense on the cold surfaces. In old systems that caused rusting from the inside, but moat manufactureres today use stainless for the exhaust systems and your coworker is running the car long enough to warm the exhaust system up anyway.

I’ll avoid the air quality issue because one Freightliner running for one 8-hour shift probably does more damage to the environment than the complete daily use of 200,000 cars…including your friend’s idling.

Not all stainless exhausts are created equal. the “stainless” muffler on my CRX has big ol’ rust holes in it, and I don’t even drive it in the winter.

Also, at idle, it may not heat the back of the exhaust system sufficiently to vaporize the water, especially in the muffler. This is why you see cop cars which idle at crime scenes for a few hours spew water out the tail pipe when they take off.

MB, you make some good points, but I think you ignore the strain the air conditioner puts on an idling engine and the increased use of the radiator fan since there is no air flow.

Please make sure that she’s putting the parking brake on firmly. She could easily bump the gearshift in her sleep.

There’s obviously a small chance that something will go wrong with the car (especially overheating) and she won’t be awake to see the warning lights come on, but I guess she’s decided that she’s okay with that risk.

If you’re worried about the exhaust, I wonder if she could use one of those hoses that repair shops use when running engines indoors in order to get the exhaust further from the car.

big trucks have elevated exhaust pipes, so the exhaust gases go up and away, not under the vehicle, but the open location should be ok as far as the accumulation of exhaust gas goes. Just an aside, some of the big trucking companies have stopped allowing their drivers to idle while sleeping. some guys working for Swift got fired down in west texas for running the engine at idle to power the ac, even though the outside temp was over 100 F. Not all trucking companies are the same.

It’s a nice job that allows a 2 hour power nap. I assume that she’s working flex time.

I wouldn’t worry too much about CO poisoning. Not with the ventilation system putting positive air flow into the cabin.

I do share concerns about the cooling capacity. As long as the fan can keep the temp in control, I see no issue with it. It’s no different than being stuck in dense traffic for 2 hours. The difference being that in this case the auto-trans gets to soak up some of the excess heat instead of adding to it.

I used to work for Swift, and what those truckers probably got fired for is disabling the idle control system. I suppose its also possible they were idling their trucks in a town or county where idling trucks is illegal. They probably left their trucks idling when it wasn’t necessary by removing the idle control system fuse.

The idle control system is connected to a thermostat, so when the interior reaches a target temperature, the engine automatically shuts off. When it reaches another target temperature, it automatically starts up again so the heat or air conditioner can run. This system also detects when the batteries are getting low and automatically starts up to charge them.

Those guys in West Texas probably got tired of having their sleep disturbed by the truck automatically starting up and shutting off, and I don’t blame them for that. The idle control systems in these trucks are not designed with driver comfort in mind. They’d be better off with generators and Swift would save money on fuel if they had generators installed. It is also possible those guys in West Texas couldn’t figure out how to program the idle control system. It ain’t easy.

When I worked for Swift, my idle control system stopped working, so I was told to pull the fuse for the system. After taking the truck to three different Swift terminals to get it fixed, they kept giving me the truck back saying it was fixed, but it wasn’t. Finally, I insisted on taking the truck to a Volvo dealership. They diagnosed and fixed the problem, a burned out lightbulb in the dashboard display, but then Swift didn’t want to pay the Volvo dealership for the work, so I sat at home an additional week while they worked it all out.

One last thing. Whether we are talking about a car or a commercial truck, the exhaust system runs under the passenger compartment, and an exhaust leak can be just as lethal in either case.

Other than using a bit more gas, I can’t see what effect the AC compressor or the fan operation would have. While the idle is boosted a bit for the comprssor, fuel is still metered by the O2 sensor.

you are so right on when you say an onboard generator is the answer to this problem for trukers, but how to make management in their air conditioned offices see it?
remindes me of the question of how to get replublican senators who live in climate controlled cars, houses, and offices, to notice how hot its getting out here in the real world.

Sorry to hear about the rot holes.

Actually, up here in NH when the weather gets real cold there are days when water drips out the tailpipe no matter how far you drive. The exhaust pipes dissipate heat so fast that the sxhaust never warms them up. Condensation is continuous.

Gas is 1 part carbon and 1 part hydrogen (bonded in a molecule). Water is 2 parts hydrogen and one part oxygen. For every gallon of gas you use, you produce roughly 3/4 of a gallon of water (roughly 1/2 the gasoline molecules bonded to 1/2 again of their own volume in oxygen). That’s a lotta watta.

But I see your point. If her exhaust is like yours, perhaps she will have premature exhaust system rusting from the condensation.