Prius A/C

The A/C needs the car to be in Ready (started) mode so that it can get power from the big battery, and as long as you have gas it'll run the ICE occasionally to keep the battery up. This includes sitting at lights.

If you just have it in ACC mode, the fan blows without cooling.

No big problem with long-term A/C use. I just worry about fan life myself, until some issue with the compressor shows up instead...

 

The Prius A/C works better than any A/C I've had in any car. It cools rapidly and keeps running even when the ICE shuts off.

 

The only time I've had my battery drain down to where the ICE needed to be on was in major stop-and-go traffic on a very hot day. The ICE does NOT come on when you're sitting at stoplights (unless they're v-e-r-y long and close together). The AC cools the car just fine when it's sitting still and the engine is off. I sometimes leave the car in "Ready" with the AC on when I have a quick errand inside a store and my mom's sitting in the car. Sometimes the engine comes when I do that (if I take a while), but it's worth it for her to be comfortable. BTW the engine will only cycle on briefly--just enough to get it out of the pink bars and then it will shut off again.

 

Instead of powering off while waiting at the dealer's this morning, I just pushed the Park button.

After 20 minutes of radio and A/C, the ICE came on for a bit then stopped. After that, it came on maybe every 4 minutes. My comfort being important, I didn't argue...

 

<div class='quotetop'>QUOTE(jeff716a @ Jun 21 2006, 10:51 AM) [snapback]274743[/snapback]</div>

Jeff, the classic Prius (and Ford Escape hybrid) have engine-pulley-driven compressors. In those, there is a 'max a/c' button to force the engine to run. I call it the 'Mom-button' because she did not like the 2001 Prius to warm up while we were stopped at traffic lights.

New model Prius a/c is engine-independent in the short term, as you say.

 

I don't know specifics, but with lesser technology cars of the past I've been told that it promotes longer life of air conditioning components to shut AC off prior to engine shutdown.
Is this still the case with today's cars, and specifically in the Prius?

 

<div class='quotetop'>QUOTE(jmccord @ Jun 21 2006, 12:07 PM) [snapback]274783[/snapback]</div>

Well, the "AC off" item you mention sounds like yet another vehicle old wives tale of the past. The only issue with leaving the A/C switch on in older vehicles is that some of them would have the air conditioning compressor engaged as you turned over the vehicle. This would place a great deal of resistance on the starter motor and make starting harder. Even vehicles that are 20+ years old had various controls, relays and switches which would not engage the A/C clutch until after the car was fully started, thus meaning that if you had the A/C switch on at startup the A/C clutch didn't engage until the vehicle was fully on. A/C clutches are electromagnets with the belt wrapped around a pully that normally spins free until the electormagnet turns on causing the free spinning pully to linked to the compressor shaft.

The Prius is basically a fully automatic, set it and forget it, vehicle. The auto climate system won't fully engage the climate system until a number of seconds after the vehicle has been put in READY mode. In the winter it will not engage the heat until there is some heat available in the core and in the summer it moderates fan speed and the recirc system and runs the compressor as necessary to achieve the temp setpoint it has been given.

Drivers need give little other thought to all of this other than what temp they want the cabin at.

 

<div class='quotetop'>QUOTE(jeff716a @ Jun 21 2006, 12:51 PM) [snapback]274743[/snapback]</div>

Putting it another way: the car has to be in READY mode (the same mode that allows you to drive) and the transmission in "D" or "P" or "B" in order for the A/C to run without draining the battery. (If the mode is not READY the engine will not run, and if the transmission is in "N" the engine can run but will *not* recharge the battery.) The A/C will run as needed to keep the cabin cool. The engine will start, run and shut off as needed to keep the battery charged. Other than that there is no correlation between the A/C running and the engine running.

 

There is a reason for turning off the A/C before you stop the car, although it may only matter in humid climates.

The heat exchanger (evaporator) behind the glove compartment can become coated with water during use. If you turn off the A/C and continue to pass external air through the system, that water will evaporate in a minute or two. You'll know because the air coming through the vents will become just as hot as the outside air. Then, shut down.

If this is not done, mold may grow on the heat exchanger surfaces, and this is not desirable. The Prius heat exchanger does have some sort of antimicrobial coating (containing silver, I believe), but even that can get overwhelmed through time.

Another source of musty smells from the ventilation system is accumulated stuff on the cabin air filter, but I presume that all here are servicing those filters appropriately.