A/C In Very Hot Areas
 

Can someone clarify the A/C system on the FEH.

I live in Texas and temps for a couple of months a year can run about 100.

Do I understand that the A/C runs off the gas engine? How does this work in real-life. I'd hate to buy a FEH and find that I'm running the gas motor to power the A/C all of the way home.

I just bought a Camry Hybrid for my wife and the A/C will get ya lookin for a sweater real quick! It runs on the Electric system. Sooooo there is no problem there.

I'm going to be replacing my Highlander in May-June and want to decide on a FEH or a Rav-4 soon.

Thanks!

Re: A/C In Very Hot Areas
 

There are two options, though the engine must be running for the air to be cooled.

The Regular AC settings (with or without recirculation) work with the hybrid system. In other words, if the engine is on, the air conditioner will run. If the engine is off, the fan will continue to blow but there will be no cooling. The blown air will remain cool for a couple of minutes since the coils are still cold, but after that it won't be so cool. The regular settings will NOT cause the engine to come on.

The Max AC setting overrides the hybrid system and keeps the engine and the AC running at all times. The engine will not shut down in Max AC mode.

As for your fuel efficiency under Regular or Max AC, I'll leave that to some of the more experienced drivers here. I will say that if you do alot of highway driving (or any driving where the engine must run anyway) it won't hurt your economy that much.

Re: A/C In Very Hot Areas
 

The AC runs off the ICE rather than the electric motor. So what TimK described is correct. However I will say that when in "regular" AC mode, even in recirculated AC mode, my FEH's air does not stay "cool" for a few minutes when the ICE is off. It stays cool for maybe 30 seconds, then the air is noticeably warmer. If I am sitting at a long light, or crawling along in EV mode, in 90+ degree heat, I do not stay cool if the A/C is off for more than a minute. I will say that when you are moving again, and the gas engine comes on, it cools down again very quickly.

Basically, it will come down to your comfort level. Are you willing to leave the gas engine off and suffer a minute or so of increasingly warm air? If so then you will probably be fine. If not, then you may be someone (like my wife) who needs to use the Max A/C setting, which will take away a good chunk of the FEH fuel savings on very hot days.

Re: A/C In Very Hot Areas
 

I agree with everything posted so far. Nothing much to add on how the a/c works.

What I have found is that I can stay more comfortable at stop lights or extended EV periods by putting the blower fan on a lower setting, 2 or even 1. Once the ICE comes back on, blast the fan to get the cabin temp back down. This adds a little to the workload but it has become part of the routine. I don't use the a/c anyway until the temp is at least 90° anyway.

I do 95% or more of my driving alone so I don't have to worry about back seat passenger comfort. When I have the wife and kids in the car, the a/c policy changes a little. :D

Re: A/C In Very Hot Areas
 

I'm suprised the A/C in the Camry Hybrid works off the electric motor. I wonder why Ford didn't do that with the Ford Escape Hybrid? But I will have to say from experience that Toyotas have the coldest A/C of any automaker, whether it be a Camry or a Tundra.

Re: A/C In Very Hot Areas
 

The Camry A/C operates with an electric compressor, it does not run off the electric motor that propels the vehicle. The same is true about the power steering system.

Re: A/C In Very Hot Areas
 

Ford realized the problem with their power steeting system too. Its run by electric. Too bad Ford didn't do the same with the A/C system. I guess they just don't use A/C all that often in Detroit. :P

Re: A/C In Very Hot Areas
 

I think there may have been more thought that went into it than you are giving them credit for. A compressor requires a large amount of power to run and if it was running off the battery, the end result would be shorter EV times and more ICE on time. With the compressor running off the gas engine, the driver at least has the option of highest efficiency versus highest comfort. More often then not, I take the efficiency.

I have also found that initial warmup ICE running time is an ideal chance to cool off the cabin using MAX a/c. Once the car is ready for EV, switch back to one of the white settings.

The power steering is a different matter - you would never want to be without it so it was run off the battery.

Re: A/C In Very Hot Areas
 

Have you ever driven a base Escape and then a Hybrid? The steering ratio on the hybrid is a lot higher, probably to minimize the amount of current required with the power assist system.

Turns that require half a turn of the steering wheel on the base require almost 3/4 turn on the hybrid. Well, maybe not quite 50% more, but it is noticeable.

Re: A/C In Very Hot Areas
 

Besides running the A/C at initial warmup, another ideal place to run the A/C is when you are descending a hill in L. When your battery is full, the computer will spin the ICE with the fuel shutoff to slow your descent. Turning on the A/C not only adds more drag, but cools you for free as well!

rb

Re: A/C In Very Hot Areas
 

If the A/C was electric, the system controller could turn it 'on' as needed, and factor in other variables too, like critical need (cabin is 10 degrees hotter than temp setting), power available (down-hill regeneration is occurring), power stored (batteries fully charged), etc.

The A/C could, then, run with the ICE or without ICE. I mean, nothing says it has to run without the ICE running, it is just an available option.

Currently, the A/C can only run with the ICE. It is that designed-in limitation, and its lack of flexibility, that I question.

Come to think of it, where does the heat come from, in the winter, when the ICE isn't running?

Re: A/C In Very Hot Areas
 

Theoretically, its more efficient to pull it off the engine. The battery energy used by the electric airconditioning system on the other vehicle gets it energy from the ICE at some point. Converting to charge in a battery and back is pretty efficient, but not as efficient as running it off the engine itself. In the end... that electric system may SEEM better, but as far as the car getting better mileage because of it, you'd be wrong.

Re: A/C In Very Hot Areas
 

The big "problem" would still be when you are in EV mode. An extended EV period with the a/c on would drain the battery more quickly resulting in the need to run the ICEto recharge. I've gotten used to it the way it is and still believe it is the most efficient way of doing it. But then, I live in New England where a/c is only "needed" for maybe 2 months a year.

As for the heat, I think it works the same way as a regular car heating system except I believe there is an electric water pump. I have shut off the engine in mine, turned the key back to the run position without starting and get good heat for much longer than a regular car.

Re: A/C In Very Hot Areas
 

What I'm trying to say is... the A/C will consume the same energy either way. So if its pulling it from the battery then its draining charge placed there by the ICE. The losses in the mechancial to electrical to mechanical might be fairly small but they aren't insignificant. So.... running your A/C on and ELECTRIC system all the time will be a bigger MPG hit then running the system directly off the ICE in the red setting.

You don't gain free energy.... Its coming from the ICE one way or the other.

Re: A/C In Very Hot Areas
 

Answer for heat is the same as the A/C. From the ICE. The difference is that the ICE has alot more thermal mass than the A/C coils and doens't cool off very fast.

An electric A/C will allow you to cycle on and off (you can do that to the ICE too). But everyone is saying you only get about 30 sec of cool air so its going to be on almost constantly. Maybe the real best option is to provide a system with some more thermal mass to it so that once the coil gets cool... it stays that way longer. Problem is it would also take longer to cool in the first place.

Re: A/C In Very Hot Areas
 

Hi All

http://web.mit.edu/newsoffice/2006/tpv.html

This is a link to an MIT study which in part, is funded by Toyota.

It is a sort of solar energy that can eliminate the need for the battery or ICE running the A/C compressor and many other electrical auto systems. The write-up says the system would be for hybrid vehicle that the ICE shuts off and trucker's who must sleep in the cabs, and run the diesel for A/C use.

A system like this would be perfect For FE!

GaryG

Re: A/C In Very Hot Areas
 

Maybe it is I see it this way...

The best of a Hybrid is in stop and go traffic, where you are spending a considerable amount of time just sitting there going no where fast.

Now, as the title of this thread states, put that stop and go traffic into a Very Hot Area. Say, its 100 deg in the shade, 120 deg on the blacktop roadway, and the sun is baking down on you. That is what I consider to be a very hot area.

Normally, the ICE would be 'off', saving gas. With A/C running only on the ICE, my Hybrid will be failing me when I need it the most; no A/C! :omg:


The only other thing to do, is to switch to Max A/C, and now the ICE would be 'on', using gas, just to run the much needed A/C. If the ICE needs to run constantly, I might as well have bought a non-Hybrid.

That's why I thought that having an A/C which runs off the electric, instead of the ICE, would be nicer.

Re: A/C In Very Hot Areas
 

Hi Walt

Here is what I do in the heat with my FEH.

In temps above 85F, the compressor will run to cool the battery while the ICE is running, so I run the cabin recir A/C. This keeps the battery functioning much better for EV anyway. If I start getting hot, you can bet the battery is getting hot, and that causes a lost in FE.

After running some tests, I found I can push the FEH in the 60mpg range with the cabin recir A/C running. It gets pretty warm in EV, but that is pushing things to the max. Now, I control EV and the ICE to meet the demand of my cooling needs. Some days, depending on the heat, I still can push 50mpg and stay cool. On real hot days, I run less EV and > than 50% battery SOC and still stay above 40mpg. Mainly just take the FEH to 43mph and go EV at 40mph so the ICE is off till I coast to 30-35mph, then restart and pulse back to 43mph and repeat. Now, sometimes I must do high speed pulse and glides (50mph down to 40mph or even higher) with the ICE ON to get the cabin nice and cool and fully charge the battery. With a fully charged battery, you can look at my Steady State test and see you still can get great FE. My next test will be with the A/C on to compare.

There are so many choices I have to drive and stay cool now. Wish I had this info last summer!

GaryG

Re: A/C In Very Hot Areas
 

You're not wrong necessarily.... but the equation might not lean as far to the electric A/C as you think....MOST of the time the A/C is running with the engine on... its only stopped at lights sometimes. So the losses from the mechanical-electrical-mechanical conversion are constant... even when going down the road compared to the losses of the engine idling at an intersection to keep the A/C on when only the days its hotter than all get out. Its hard to say... It certainly SEEMS like the idling might be the most wasteful--but you'd be suprised how often such assumptions are wrong.

Also... hybrids aren't efficient JUST because they shut off the engine at intersections. They also have more efficient smaller engines because of the electric low end torque of the electric motor AND there is the regenerative breaking. The 6-cylinder 4WD gets something like 19MPG on the freeway. I do 28-29 EASY in my 4WD hybrid and the engine is running all the time.

So... its not like you are giving up EVERYTHING hybrid if you turn that A/C to max :D

Re: A/C In Very Hot Areas
 

WOW.... Interesting comments!

I'm going to have to think about our family needs a bit before I make a commitment to the FEH. I really need a small SUV to haul our family "stuff" from time to time. However, most of my travel is commuting 15 miles each way.

For those of you who haven't tried the TCH, I've got to say that the A/C will get you so cold that you are looking for a sweater, even in those 100 degree days. The sytem does run on the electric side of the house. As it relates to A/C, the ICE only comes on when the battery need charging.

Thanks!

Re: A/C In Very Hot Areas
 

15 miles isn't bad. I commute about 9 miles to work every day. I have the 4WD FEH and I average about 30 MPG. If I go just a little further I probably get about 32-34. I haven't done any of the air pressure tricks for the tires, and I drive pretty "normal." As for the A/C. When its on its pretty darn cold. I have to turn it down. At intersections I find the recirculate mode is plenty unless I'm sitting for 4 or 5 minutes or its extremely hot outside. If it gets that way I just reach over and pop on the max A/C for a minute.

Its completely under my control and I find I rarely have to pop on that max A/C.

Re: A/C In Very Hot Areas
 

It is true that all the energy used comes from the ICE, however, I think that an electric A/C could actually be more efficient (as opposed to ICE-driven Mac A/C) in terms of MPG.

The battery gets charged while the ICE is running and by braking. Now if the A/C could stay on while the ICE shuts off when it isn't needed - eliminating the need to run the ICE solely for A/C (very wasteful...gas burned for no miles gained) - this shift would still allow higher overall efficiency by using the stored energy in a situation where the ICE isn't needed.

I think it's similar to driving in EV mode, shifting traction to electric at slow speeds (where the ICE is less efficient) and leaving the ICE off so as not to waste gas, is a better overall option.

It's the shift/blend of electric and ICE power that makes hybrids what they are... that's why a hybrid can achieve much higher MPG compared to a conventional vehicle, even though both vehicles derive all their power from the ICE.

Of course, it depends on the type of driving you do and your A/C usage. Electric A/C might be more fuel-efficient for some and worse for others.

Re: A/C In Very Hot Areas
 

I'd be real interested to know what size the electric motor is that drives the a/c compressor in the Camry. Any experts out there know what kind of horsepower it takes to run a car a/c? I know it is a significant amount since you can feel the difference when the compressor kicks in on any car (you can see it in the mpg too). What about Camry owners - what kind of difference do you get in your EV mode when you are using a/c versus when you are not?

Re: A/C In Very Hot Areas
 

The TCH has an ECO mode for the A/C that somehow avoids a big hit on the mpg. Monday I drove over an hour (about 30 miles in 105 to 110 heat in freeway rush hour traffic, very humid too...) with the A/C set to 77, ECO and recirc on and did not notice any drop in my tank mpg. I park in a parking structure so the A/C doesn't have to work so hard to keep it cool.

If the car is parked in the shade, I honestly think the mpg hit is under 1mpg for the A/C running in ECO mode. Now if I park in the sun, I notice a big hit - a good 2 or 3mpg drop is my estimate. It takes a lot of energy to remove all that absorbed solar heat, and while the A/C blows cold, it takes time to cool down.

I'm curious too about the compressor sizing and power managment. I can't tell if it cycles like a belt driven compressor or just 'throttles back' and uses less power to regulate the temperature.

Re: A/C In Very Hot Areas
 

Nash, since you have both types of vehicles - which a/c system do you prefer? Which seems to effect gas mileage the least? Do you see any drawbacks to one over the other?

Wat about impact on performance?

Thanks

Re: A/C In Very Hot Areas
 

I prefer the TCH electric A/C, mostly due to the constant cooling in EV mode. Both cool down, and perform about the same. Our FEH drops from 30mpg to about 28mpg when running the A/C all the time. I don't need A/C in the morning with the TCH, so I'm not sure about the mpg hit, but my feeling for it is they both have about a 2mpg hit if you park in the sun.

I suspect the belt driven A/C compressor on the FEH will not last as long as the electric A/C TCH compressor. The belt driven compressor has both a clutch and shaft seal that wear out. The TCH compressor appears to be a sealed unit, with no shaft seal or clutch to wear out.

Edit: I have FormulaOne Pinnacle 35% tint all the way around (not the windshield!) as the first thing I noticed was how much heat came in the TCH rear window. The tinting dramatically reduces the heat and improves the A/C comfort.

Re: A/C In Very Hot Areas
 

That's a good point. :lightbulb

With a ICE driven compressor, you have that electromechanical clutch to deal with. Plus, an ICE driven compressor has to be "over designed" with not under compressing the FREON at low ICE RPM's, while not over compressing the FREON at high ICE RPM's.

The electric driven compressor doesn't have the clutch, and runs at a fixed, known, RPM. A much more simple and, I would venture a guess, more efficient design.

Re: A/C In Very Hot Areas
 

Since I'm not unhappy with the way it works in the Escape, I won't quite say I wish it had electric a/c but I am starting to be a believer that it may be better.

We are allowed to change our mind around here, right?:D

Re: A/C In Very Hot Areas
 

So on the TCH, is the A/C for the EV battery run off the same electric compressor as the cabin air? I assume it would be.

One appeal of the electric A/C is the ability to run the air without the ICE when the car is parked. Many times at work during lunch hour I see people sitting in their vehicles, engine running, A/C on, reading, napping, or talking on the cell phone. That's something I personally wouldn't do, but with electric A/C it seems somehow less wasteful than idling the engine for an hour. I wonder how long the electric A/C can run on a full battery?

Don

Re: A/C In Very Hot Areas
 

I need to investigate the TCH battery life when running theA/C only. We've only had our car 2 weeks. The ICE turns on and off frequently as needed. It is fairly quiet. You can be sitting at idle (with the radio on) and not really know what you are running on unless you look at the monitor.

Re: A/C In Very Hot Areas
 

[QUOTE=nitramjr] Any experts out there know what kind of horsepower it takes to run a car a/c? QUOTE]

Around eight horsepower.

Re: A/C In Very Hot Areas
 

I think it comes down to a matter of efficiency. The energy to run the AC is essentially all coming from the ICE, so the question is whether it is significantly more efficient to run the engine to power the AC or to convert the energy to the battery and then back to an electric AC. The engine doesn't seem to be particularly efficient at charging the battery on its own so I'm wondering if it doesn't make more sense to run the ac directly off the ICE?

Also, running the AC on battery would further drain a battery that doesn't seem to have much capacity to begin with. For stop and go driving I just don't see the vehicle being able to effectively maintain a charge that can both assist in acceleration and run the AC at the same time. I know if I had electric AC in my MMH the ICE would be running alot at idle to recharge the battery anyway.

Re: A/C In Very Hot Areas
 

TimK and Teester: Don't forget about the regenerative braking. Sometimes it sounds like you guys are saying the only way the High Voltage battery gets charged is from the ICE. I would like to think that the regen braking does more of the charging.

Re: A/C In Very Hot Areas
 

I live in San Antonio, Texas. It's hot here every summer and doesn't let up until, oh, maybe Halloween. We get an occasional cloudy day but it remains humid, otherwise the sun's beating down oppressively.

And yet I don't feel my hybrid is "failing me when I need it most." I run the fuel economy-friendly A/C setting anytime I'm in the vehicle, unless the vehicle's been parked for a long period outside, in the sun. In those instances, the vehicle has generally been parked a good while, and the ICE has to run anyway for a bit, so I kick her into Max. A/C to cooldown quick, then switch back to fuel economy friendly mode for the rest of my trip.

I avoid using Max. A/C but I don't view it as a hybrid-killer. Use it if you need or want, just know it has an affect... like anything else in any vehicle. I keep my fan set on 1 (lowest setting) and find the A/C in fuel economy mode even at not-full coldness setting (all the way left in the blue section of the climate control knob) still chills me to the point I fiddle with vents. :)

For long EV periods at peak daytime heating, with people in the back seat, yes I will click in to Max. A/C as needed... use it when you need it. It's like having to aggressively accelerate occasionally due to either traffic or to avoid a potential issue -- it's not fuel efficient but use it when you need it.

Just my 2 cents. I'm VERY temperature sensitive, having a very narrow range of temperatures where I feel actually "comfortable" -- neither too hot nor too cold. I can tolerate my FEH just fine, and as mentioned earlier, have it overcool me almost as often as to cancel out the EV segments where I'm parked awhile and have to ponder, "Max. A/C or wait til the heat level builds a bit and open the windows 'til I'm underway again?"

Your mileage of course may vary.

I will note that my FEH is my first vehiclle that I am definitely getting the front windows tinted on. Check the legality of doing so in your state, and to what light transmittance level (eg. the factory tint on the FEH is reportedly something like 20% or 24% light transmittance, which means 20-24% of light rays are transmitted into/out of the tinted glass; for comparison, "limo tint"/black is 5% light transmittance.) That should help with keeping the oppressive sun from heating up the cabin as quickly as it otherwise will, and avoid one's body feeling hot due to sunlight streaming in on one's legs/arms when the cabin air temperature is actually not fluctuating.

Re: A/C In Very Hot Areas
 

Well, if you trace it back, the energy recovered by regenerative braking is coming from the inertia of the moving vehicle.... the vehicle is moving due to the ICE.

There is no other source of energy input other than the ICE.

Re: A/C In Very Hot Areas
 

Exactly... You don't even get all of the energy back due to friction losses.

Re: A/C In Very Hot Areas
 

I'm with 'GeekGal.' I'm not in a very hot area, but our daily temp has been over 90 for most of the last three weeks. Even on high EV trips, if I have the A/C on internal recirculating, I'm fine. It takes about 5-10minutes for the engine to kick off when I start the car. During this time I'm getting max cooling anyway. Then, I keep as much of the cool air in the car as possible by shutting off the outside vents. The way I figure, if you've already cooled the air, might as well still use it.
Actually, I think the air conditioner in the Escape is more powerful than that in my Explorer, or at minimum the vents are set to hit you more. I find that I have to dial down my A/C on trips because I get too cold.

(I'll admit one caveat-- I'm comfortable at 80 deg if I'm sitting still. I expect the winter gas mileage will be less than this summer.)

Re: A/C In Very Hot Areas
 

Teester and Randy covered my thoughts on the ICE....as for the AC, with my 7mo old son in the back seat I can get away with no AC in the mornings, but on the way home at 4:30pm and 90+ temps it is Max AC the whole way home. This ends up giving me a FE of about 24MPG for city driving on Max AC.

Re: A/C In Very Hot Areas
 

This really helps a LOT. It is not legal where I live but I have done it for years anyway & never had a problem. I tinted the front windows at 20% on my 05 FEH & added a windshield band. I also added in-channel vent shades.


These changes made a DRASTIC difference in comfort in 90+degree hot sun conditions.

~John

Re: A/C In Very Hot Areas
 

http://www.iwfa.com/iwfa/Law_Chart/L...art%204-06.pdf

Here is a chart of state tinting laws. I can't vouch for its current accuracy.