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Comments
The A/C compressor can be disabled indefinitely so it does not operate automatically in normal automatic mode or in defrost/defog/demist mode.
With these settings the A/C can be turned off manually and will remain off indefinitely until it is manually turned back on. Once turned on it will operate continuously just as it otherwise would. As shipped the A/C will also operate automatically with the defrost/defog/demist function with no indication to the driver of same.
Operation of the A/C during the winter months is needless except for the remote possibility of it being able to dehumidify the incoming airflow to a level which prevents windshield fogging. Since most occasions of windshield fogging is the result of system "upset" (loading a couple of cold, wet, and sweaty snow-skiiers with their soaked clothing, etc.) or in many cases the result of A/C operation being discontinued due to declining OAT.
Intermittent use of the A/C only during defrost/defog/demist mode is a catch 22 of itself. In the rare case wherein the incoming air's dewpoint is such that the A/C can provide a reasonable level of dehumidification when the normal operation mode is resumed the A/C operation will stop. That will result in all of the previously condensed moisture remaining on the evaporator vanes to evaporate into the incoming airstream often resulting ain a reoccurance of windshiedl fogging.
Another new feature is that the dealer can change a custom setting wherein the system will not automatically switch from footwell, heating mode, to dash/panel outflow, cooling mode(***). The cabin temperature control only responds to air temperature or thye sun's radiant heating effects. The human comfort equation is much more complex than can be rsolved by just those two parameters.
The effects of radiant heating (or lack thereof) from the exterior and interior "landscape" surrounding your body also play a very great part in establishing human comfort. On a cold dark night with the landscape covered with snow the system, driven only by its measurement of interior, cabin air temperature, will almost always shift, first, into mixed footwell/dash outlet mode, and then into full cooling mode, dash airflow outflow mode, once the cabin temperature closely approximates your manual temperature setpoint.
As many of you have already no doubt noticed, that can be quite discomforting to you and your passengers.
But there is yet another important aspect of this feature, heating/cooling mode parameter setting. In full cooling mode, which the system would otherwise almost always default into as the cabin temperature reaches your setpoint, no warming airflow reaches the interior surface of the windshield.
It can become extremely dangerous to allow the windshield interior surface temperature to decline due to the onrushing COLD outside airflow during wintertime operations. Keeping the system in footwell, heating mode will result in a significant level of airflow being continuously routed to the windshield thereby keeping it well above the dewpoint of the cabin atmosphere.
You may note that in your owners manual is a new (as of 04?) note of caution. Since the A/C will shut down automatically if the outside temperature should decline to or below the freezing level the newer Denso climate control systems will automatically switch a portion the system outflow to the interior surface of the windshield just as the A/C is disable.
A bit of shutting the barn door after the horse has galloped off down the road, that is.
Or actually it can be very much worse.
When the A/C is disabled in thsi manner any previously condensed moisture remaining on the evaporator vanes, 10,000 square inches thereof, will begin to evaporator into the incoming airstream. Absent your having had the dealer make the parameter change from the factory default the windshield interior surface may very well have already been chilled to well below the dewpoint of the super-saturated airstream now routed, automatically, in its direction.
But never fear, there is yet another parameter that the dealer can set for you that will help to defog/demist the windshield. The dealer can set a custom parameter which will cause the blower speed to automatically increase when you select the defrost/defog/demist mode.
Now if we could just get them to recognize that the airflow heating level to the windshield should also go up simultaneously.................
*** I would be very interested in the results if anyone choses to have this parameter set to prevent an automatic switch to cooling mode. I assume one can still manually switch to cooling mode. My question is does it operate in the same way as the A/C disable custom parameter?
If I manually switch to cooling mode will it thereafter automatically switch back and forth as it otherwise would until I manually turn cooling off?
Thanks,
Chintan Talati
Corporate Communications
Edmunds.com
Thanks,
Chintan Talati
Corporate Communications
Edmunds.com
AWD vehicles a portion of the engine torque is (supposedly) routed to the rear, especially under high torque circumstances, so the level of halfshaft windup will be lessened.
Additionally the RX400h uses electrically powered stearing and while the information doesn't so state I strongly suspect the stearing control ECU is programmed to compensate for torque stear. Given the other uses (***)the EPS, electric power stearing, is put too, I can't imagine it isn't also used in this way.
*** Under high acceleration most of the front tires' traction coefficient will be dedicated to forward motion with little remaining available for turning, lateral, acceleration. So in this case, hard/rapid acceleration, the level of power assist for stearing is significantly reduced as an indication to the driver that rapid or hard stearing inputs are not advisable.
Biasing against/of the ease of turning the stearing wheel is also done during VSC activation as a method of "advising" the driver of the correct way to recover or alleviate the condition that caused the VSC system to activate.
Most modern day systems, especially SUVs since they are more prone to roll-over, are also somewhat "pre-emptive" when it comes to a tight turn under hard acceleration in that they will quickly step in and dethrottle the engine to prevent an entry into the parametric level that might lead to a roll-over.
All this makes it highly unlikely that you will ever experience any significant level of torque stear in any RX400h, even the FWD only version.
But to answer your basic question, FWD vehicles will always be more hazardous, much less beniegn in the handling department when things get dicey on an adverse surface roadbed, than a RWD vehicle. So any vehicle that is FWD biased, as the RX400h clearly is, will always benefit from also having a significant level of drive torque provided to the rear wheels.
bobgail
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A national finance magazine is looking to interview consumers who are looking to purchase a hybrid vehicle and are looking at it from a financial standpoint, hoping to save money from the high cost of fuel. Please send an e-mail to ctalati@edmunds.com no later than Saturday, June 10, 2006 by 5:00 PM PT/8:00 PM ET containing your daytime contact information and the hybrid vehicle you are considering.
Thanks,
Chintan Talati
Corporate Communications
Edmunds.com
Please remember to check the discussion list inthe group to find an appropriate discussion before posting. Thanks!
Lexus RX 400h Test Drive - What Did You Think?
New Lexus RX 400h Owners - Give Us Your Report
New Lexus RX 400h Engine Stuttering/Missing
RX 400h GPS/NAV Issues
So before you post in this main topic, please check the discussion list for an appropriate discussion. If you have an issue to bring up thatwe don't have a discussion for, please feel free to create one or drop me an email by clicking on my username with your suggestion.
Thanks for your hlep and understanding while we move the furniture around a bit!
Lexus is pleased to offer you the opportunity to talk with Bob Carter, Lexus Division leader responsible for our all-new performance hybrids. The live chat is for hybrid enthusiasts as well as those interested in learning what this technology means for them.
The chat will be on Tuesday July 25 at 9pm ET/ 6pm PT
Join us at The New Era: Lexus Hybrids live chat event!
I'm the proud owner of a new 2007 Lexus RX400h. Just got it this weekend and am very happy with it so far.
But, I have a question that came to me 3 hours after I purchased the car:
Does anyone know if the electric motor in this car (or other hybrids) will create electro-magnetic fields that can prove harmful to pregnant women or children? (i.e. similar to how living near power-lines can potentially cause cancer in children and adults?) Would love to know if anyone has thought about this? Does anyone know how to measure the EMF / magnetic fields in the car whlie driving? I'd like to compare it to other EMF sources and see if this could potentially be an issue.
What are your thoughts?
To date, neither an exhaustive web search nor the services of a crack librarian at the University of Texas have been able to unearth precise measurements of electromagnetic fields, or EMF, in hybrids. What you do with this knowledge, or lack thereof, depends largely upon your personality. Currently, the public can only be sure that the electronics contained in the vehicles meet FCC standards for electromagnetic interference (EMI) with other electronic devices.
Wow, where did you find the study to support this statement?
Wow...Double that, WOW..!
I have NEVER seen a more direct admission of the hazards of engine braking on a FWD or front biased AWD in my life, never really expected too, from FORD yet. Good-o.
You should note that the FEH/MMH regenerative braking is significantly reduced ONLY at, near, or below freezing.
Regenerative braking is instantly reduced to zero if ABS needs to release the brakes to prevent lockup. But what about the ICE itself, does it raise the ICE RPM simultaneously to prevent actual engine braking?
Now I am very sure, certain, sure, I never want to drive a FWD or front torque biased AWD in wintertime conditions.
For a reply, see my response in the Ford Escape Hybrid forum. I won't cross post it here.
one-of-a-king glitch? anyone else had this problem
www.toyota.com/html/hybridsynergyview/2006/fall/battery.html
What does this mean for us owners with regard to future support, maintenance, and trade-in value?
If I do have to get the hybrid, I have some concern about driving on our snowy driveway and private road and damaging the hybrid drivetrain. Does it have protective mechanisms built in to prevent snow-based wheel spin from damaging the car?
It's entirely possible, maybe even highly probable, that the RXh will yield better AWD capability on adverse, wintertime, ice, packed snow, roadbed conditions.
For that matter, I wouldn't willingly take either off-road, but if I did have to choose it would be the RXh for brief off-road excursions.
The hybrid AWD is pure electric, and the electric motors will overheat with too much continuous use. Hence the conventional RX would be a better choice if one were planning on using AWD on a consistent basis, such as frequent trips to the beach, for example.
When the motors overheat, AWD is disabled until they cool down.
And remember that the AWD RX330 series does not have a VC so the brakes and rotors are likely to overheat quickly in your "off-road" circumstance.
OK, so you get an extra 10 seconds of AWD. It still it not advised (BY LEXUS) for any off road use. Those motors are not made for any strenuous, continuous use (such as found in true off road).
Not sure what you mean by "VC" (maybe VSC?), or why you are mentioning the RX330 on a RH400 forum. But brake fade is a completely different issue. We are speaking of acceleration here, not braking.
Not if its an RX330 which does not have a VC, Viscous Clutch, so the brakes must take on the full load of apportioning engine torque front to rear.
What I cannot understand is the use of regenerative braking during periods of coasting. How does the hybrid system know of my intent?
What if my intent is to extend FE by coasting slowly to a stop at that upcoming stop sign or traffic light. It seems to be that since regenerative braking can NEVER recover enough energy to overcome the fuel savings I might attain by simply coasting it would be better to only use regenerative braking instead of friction braking or along with same.
Or why not a clutch-like control wherein I can "tell" the system my intentions. Regenerative braking unless I activate the "clutch" indicating my intention to coast and thereby increase FE.
Is there a break-in period for the 400h (mileage wise)? About how many miles do we have to have before hooking up a trailor hitch and hauling some things. I appreciate your help.
JB
Most break-in instructions want you to vary the road speed for the first thousand miles so the engine rings don't seat just at a narrow RPM range. How would this work with a CVT wherein the ECU can operate the engine at the most optimum RPM regardless of roadspeed?
What are your takes on the Extended warranty? Is it worth purchasing it with the car? What would be a reasonable price to negotiate for? Thank you in advance.
JB
When I bought my new 4Runner and new Subaru Outback, Folks on Edmunds Forum steered me in the right direction to purchase my extended warranty elsewhere and I got a great deal. Any ideas or suggestions of dealerships that have a deal on the extended warranty? Any idea on what is fair to pay for the yearly perma-plating? Thanks!
The break-in period for a Lexus 400h????? let me QUOTE YOU ............ " to extend the life of the vehicle, the following precautions are RECOMMENDED to observe:
for the first 200 miles * Avoid sudden stops.
for the first 500 miles * Do NOT tow a trailer. ( that answers that question above!!)
for the first 1000 Miles * do not drive at EXTREMELY high speeds.
* Avoid sudden Acceleration.
* Do not drive continuously in the LOW GEARS.
* Do not drive at a constant speed for extended periods."
These are the Lexus suggestions......... printed in the owners manual.
My own philosophy is that if you have to think twice about whether or not it's good for the Vehicle ....... Don't do it!!!!! Ask your sales rep!!!!!! ....... and if they don't know ask me!!
Just my opinion .......
Tom Quinn
Internet Sales
Pohanka Lexus, N VA
Tom Q
EXACTLY...!
My point was/is what good does the above do if the CVT can, and apparently does, maintain the engine at a relatively constant RPM regardless of road speed?
With an ordinary gearbox the engine RPM MUST vary with roadspeed. With the hybrid "CVT" the engine RPM is kept within a fairly tight range which results in the best FE.