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| This is a discussion on Prius A/C operating details within the Gen II Prius Main Forum forums, part of the Gen II (2004-2009) Toyota Prius Forums category; How exactly does the Prius A/C system really work? For instance, if you ask for a low speed fan A/C ... |
Prius A/C operating details
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#1 |
| Join Date: Jun 2006 Location: Walnut Creek CA
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Friends: 0 | How exactly does the Prius A/C system really work? For instance, if you ask for a low speed fan A/C system to perform, does it's power demand start to lessen as the car's interior approaches target temperature? Also, I am quite sure that the compressor shuts off, once target temperature is achieved - - Right? |
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| | #2 | |
| Senior Member Join Date: Feb 2004 Location: Kent, WA
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Friends: 0 | <div class='quotetop'>QUOTE(fphinney @ Sep 29 2006, 11:15 PM) [snapback]325944[/snapback]</div> Quote:
Prius air conditioning system By TonyPSchaefer Let me tell you that I was impressed with the Prius air conditioning system right off the bat. Working for a building controls engineering company, I immediately related with what the Prius was thinking. There are some differences in the details between building controls and car A/C systems, but the basics are pretty much the same. Basically, it works like this: if the interior of the car is hot and you want it cold, the fan and compressors come on full-bore. On the other hand, if it's cool in the car and you want it slightly cooler, then they all come on slightly. As the temperature in the car reaches the desired setpoint, Prius recognises that it's getting closer and adjusts the compressor and fan accordingly. In that way, it eases into the proper temperature rather than running the fan all-out and then suddenly stopping (which is what most residential air conditioners do). In an over-simplistic way of thinking of it, think of the fan speed as the proportional difference between SETPOINT and CUR-TEMP. For example: SETPOINT=65º and CUR-TEMP=90º creates a high proportional difference resulting in a high fan speed. SETPOINT=65º and CUR-TEMP=70º creates a lower proportional difference resulting in lower fan speed. The Prius most likely recalculates several times per second (I'm guessing) Secondly, you might notice that the vents blowing the air change. Rather than blowing a bunch of air out of the dashboard vents and straight into your face, Prius will adjust so the air is coming out of the windshield vents and at your feet. As the airflow rate decreases, Prius will reroute the air to the vents. This is very smart since the sensation of comfort is a combination of temperature and air movement. Doing this, Prius can keep you comfortable simply by moving air, chilling it a little less and using less energy. Just like the variable transmission, you can think of the A/C as a variable system. Basically, if allowed to do it's thing without human interferance, it will work extremely efficiently.
__________________ SeaSalsa 04' Salsa Red Seattle Area | |
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| | #3 | |
| Join Date: Jun 2006 Location: Walnut Creek CA
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Friends: 0 | <div class='quotetop'>QUOTE(seasalsa @ Sep 30 2006, 08:00 AM) [snapback]325980[/snapback]</div> Quote:
SeaSalsa - WOW! Thanks, Great reply. I seem to have a little trouble getting satisfactory replies to questions & problems on this site. Other than that, this site is pleasantly unique. The Prius never ceases to amaze me. I keep on finding out more & more fascinating details about this engineering marvel! You made my day! | |
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| | #4 |
| Moderator of the North Join Date: Oct 2004 Location: Canada
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Friends: 20 | Not to mention that the Prius' A/C system is two-tiered. This means that during the winter (which is when this system shines), your windows won't fog up. How? When you start the car and ask for heat, the system goes into recirculation mode and you see the recirc symbol on the dash. However, while the air directed to the feet is recirculated, the air directed to the face is fresh air which means that the interior can heat up faster because of the recirculation but your windows won't fog (or defog faster) because fresh air is being directed at the face level.
__________________ 2005 Tideland Pearl Premium Package as of 25th Oct 2004 VVT-i Emblem, Sport Pedals, OEM All-Weather Mats, Cargo Mat, EV Mod, JDM Prius Interior Footwell Lighting, DICE iPod Integration Kit, LED licence plate lights, Phillips Vision Plus ![]() 2008 smart fortwo passion coupé as of 28th Apr 2008 Foglights, dash pods, leather seats, OEM rubber mats, BRABUS alum. handbrake, LED licence plate lights & dome lamp |
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| | #5 |
| SuperMID designer Join Date: Dec 2003 Location: Yokohama, JAPAN
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Friends: 5 | Following is a good article by Denso engineer... http://www.epa.gov/cppd/Presentations/Mats...%20inverter.pdf Ken@Japan |
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| | #6 |
| Junior Member Join Date: Apr 2008 Location: Austin
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Friends: 0 | Hello, I have a Prius 2006 and I am getting ready to buy a new one. I have two Questions: 2008 or wait for 2009? any opinions? Second question, has anyone had trouble with a mildew or mold smell from the AC vents when car is first started? Thanks, Lisa |
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| | #7 |
| - Join Date: Mar 2004 Location: United States
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Friends: 0 | It kinda depends on why you're waiting. I'd expect that the '09 is essentially identical to the '08, except that it will cost more. And if it does have major changes, do you really want to buy one of the first ones? Mildew can grow in the A/C in a damp climate. It helps a lot to periodically run the heater for a minute or two before shutting the car off, and to bring in outside air when the outside air is dry. |
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| | #8 | |
| Member Join Date: Mar 2008 Location: Austin
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Friends: 0 | Quote:
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