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Hybrid Vehicles Lexus RX 400h Lexus RX 400h
2334 messages, Last post on Oct 11, 2009 at 10:42 AM
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Replying to: hendjaz (Oct 29, 2005 12:39 pm) Otherwise agreed, as long as the Rh and OAT is in the range wherein the A/C can efficiently dehumidify the incoming airstream the Toyota/Lexus system will work perfectly fine. But that probability becomes less likely as the OAT declines below ~45F and impossible below about 35F. But the real problem occurs just below that 35F point when the A/C is totally and completely disabled by design (it wouldn't be functional anyway). The only way to defog/demist the windshield beyond that point is to throw HEAT at the windshield, lots of it initially until the windshield is fully defogged and then enough hot flow afterward to maintain the windshield interior surface above the dewpoint of the cabin atmosphere. The potential problem that I foresee is that just as, simultaneously with, the Lexus climate control switching the airflow to the footwell and windshield (presumably from dash, cooling, airflow mode) the A/C compressor is being disabled. The evaporator might be covered with condensate as a result of the previous A/C operation and now that condensate will begin to evaporate into the cold and dry incoming wintertime airflow. Super-saturated airflow that a substantial portion thereof is now headed for a COLD interior windshield surface.
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Replying to: wwest (Oct 29, 2005 4:54 pm) |
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automatic climate control. 2005 RX330 owners manual, page 246, right column. "The "Floor/Windshield" air flow mode may be applied automatically, if the outside temperature is lowered (??) down to below 0C (32F). This is not a malfunction. "The Floor/Windshield" air flow mode turns on the defogging and defrosting function with the purpose of cleaning(??) your front view for safe driving". This firmware change has arisen because too many of us, all the way back to 93, were experiencing unexpected and sudden windshield fogging shortly after the A/C is automatically disabled as the outside temperature declines below ~35F. Once the A/C is disabled it is already too late, but I guess we should give Toyota/Lexus/NipponDenso an "E" for effort. The best procedure for owners to use is to manually select the combined mode, Floor/Windshield, once it is obvious that the outside temperature has declined below ~45F. That way the interior windshield surface will be preheated in in the event the outside temperature continues to decline and the A/C become inoperative. Actually I find that the idiot thing remaining in cooling mode, coolish and dry airflow from the dash outlets, is extremely discomforting during predominantly cool or even cold weather. I suspect no one at the corporate engineering level of any of these companies is aware of the adverse effects of radiant cooling (lack of radiant heating, actually) on the human body.
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The best way to stay in control of humidity and temperature is to take it into the service center and have them set the user option for Automatic Airconditioning to OFF. That way it will not go switching inot to AUTO mode when you least expect it, and you can drive around in the snow with the AC on if you want to. It will not switch off because it thinks you are cold enough. |
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Replying to: wwest (Oct 30, 2005 3:17 pm)
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Replying to: falconone (Oct 31, 2005 4:31 pm) |
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Replying to: rx400hfan (Oct 13, 2005 10:32 am) |
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I'm not sure if this is the best place to post this question, but it seems that this a thread on power-train. My dealer was just notified that they have been allocated 2 FWD 400h cars. In looking at the brochure, the 0-60 time is somewhat slower, the weight is lower, and the mileage is higher. I'm not too concerned about 0-60, but rather rolling acceleration (e.g., 30-70). Any thoughts on the relative merits of AWD vs. FWD (aside from the obvious off-road and snow capabilities, neither one of which is important to us)? I know this is a duplicate message - I first posted it as a response to a previous thread) |
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If you dont care about snow, none of the 400h can go off road anyway the 2wd should be a great vehicle. The 4wd 400h is mostly front drive anyway probably 90% most of the time. I think you will find acceleration excellent in the 2wd also especially at speed. You will have the added benefit of higher gas mileage, and i think you should bargain harder on this vehicle as t he 4wd is more popular and perhaps you can get them to come down off msrp. I own a 4wd 400h with 4500 miles and its an incredible car, i seriously think you should go for the 2wd if it is optioned the way u want.
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Replying to: katzjamr (Nov 03, 2005 11:17 am)
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