First off, if the front window defogger is selected, is there any difference whether the A/C button is on or off? It seems to be on regardless, as long as the defogger is selected. In my old car, I would usually just have the vented air (non A/C) come out there so it's not blowing right at me. In the Prius, it seems to automatically turn on the A/C (even though it doesn't show that it does so on the screen). Also, do you think it's bad to sleep in the car w/ the A/C running? The engine only starts for a short while every so often, and it doesn't use much gas. I was just wondering if it's somehow bad for the car or the battery.
I agree that the AC compressor appears to come on as needed when the windshield defroster is turned on. It's not bad for the car or the battery to leave the AC on overnight as long as the car has sufficient fuel in the tank. It might be bad for you if carbon monoxide is able to make its way into the passenger cabin while you are sleeping. If you intend to camp in the car then it might be helpful to have a CO alarm in the car.
+1 on what Patrick said. A longer version: Your Prius, like most contemporary cars, runs the air conditioning whenever windshield defrost/defog is selected as it dehumidifies the air which along with some heat prevents further fog/frost on the inside of the windshield. Other than seriously reducing your daily/trip/lifetime FE/MPGs, running the air conditioning with the parking brake set, the car in Park, and in the Ready condition (on flat ground, not in a flood plain) should not hurt your Prius. As to sleeping in your Prius, the A/C compressor runs off the HV battery which is recharged from timt to time as necessary by the engine turning Motor-Generator 1 as a generator. If you run out of gas during the night, the HV battery will be drawn down to the minimum allowed by the HSD, and the car will shut down. Being in the Ready mode will also put a constant small load on the 12V battery which is kept charged from the HV battery. If you should find yourself in the unfortunate position of both the 12V and HV batteries both being "dead," you may need a trip on a flat bed truck to the nearest dealer to set things aright. This would seriously hurt your wallet/pocket book. I would say that it would be unwise to plan to run the A/C overnight with less than 4 "pips" on the gas/guess gauge. See this thread for more info on making your overnight the most enjoyable. Enjoy your stay at Motel Prius.
Thanks. The carbon monoxide was one thing I was worried about. I double checked around the exhaust pipe to make sure it was clear, but the alarm would be a good addition. I also really want some magnets and a screen. In the past, we've slept in the trunk, but this time we folded back the front seats, stuffed tons of clothes & other soft stuff to make it level (one good thing about having a girlfriend who packs tons of clothes, lol), and topped the whole thing off w/ our Thermarests. A few sheets, blankets, and sleeping bags... and it was quite comfortable!
Turning on front defrost also turns on A/C. If you then press the front defrost button again it will turn off, leaving A/C auto on. That shows it was turned on when you used front defrost. As far as curtains, in the cold, don't use defrost. The windows will fog up and you won't need curtains.
Never a good idea to sleep in a vehicle while the engine is running. Carbon Monoxide is an odorless killer.
Well, I've done it. The exhaust is outside the car, and if you look at the Prius ratings, it hardly makes any carbon monoxide at all. Very nicely controlled combustion.
