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Toyota RAV4 2008

174 messages,  Last post on Aug 01, 2009 at 4:51 PM

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What is this discussion about? Toyota RAV4, SUV

Messages Page 14 of 18

#125 of 174 Re: Audio Question - Aux (MP3) input [amygud] by dtown

Feb 14, 2008 (7:57 pm)

Replying to: amygud (Jan 09, 2008 8:29 pm)
Here is the info you need for the noise problem. http://www.rav4world.com/tsb/2007/AU004-07.pdf
If you cant open this link, its TSB ( Tech Service Bulletin # AU004-7. Your dealer will know what that means. They should resolve your problem at NO cost to you.

#126 of 174 Weak Ventilation Fan by normkol

Feb 26, 2008 (6:16 pm)

Does anyone else feel the ventilation fan in the Rav4 is weak?
 
I just got my 2008 last week, and it struck me immediately that I need to use the 3 or 4 position on the fan, the lower two don't put out much air.
 
I checked another Rav4 on the showroom floor tonight, and it is the same.
 
Anyone feel the same?

#127 of 174 Re: Weak Ventilation Fan [normkol] by wwest

Feb 27, 2008 (11:13 am)

Replying to: normkol (Feb 26, 2008 6:16 pm)
Most modern day HVAC systems use the A/C all year around, except with OAT below ~34F, for purposes of dehumidifying the incoming airflow. The SLOWER that airflow moves through the A/C evaporator the higher is the probability it will be cooled to its dewpoint and therefore somewhat dehumidified.
 
The second issue is to have the lowest noise level possible.
 
I find it best to keep the A/C COMPLETELY disabled during the winter months, run the system initially in automatic until the blower starts up (engine coolant reaches 130F) and then switch the system to MAXIMUM heating and into combined footwell/windshield outlet airflow mode. With automatic climate control systems the blower speed will go into MAXIMUM mode and it is best to lower the speed to reduce the noise level to something more acceptable.
 
As the cabin temperature rises closer and closer to my comfort level I incrementally lower the temperature setpoint. That would usually be ~72F If it were not for the need to keep the interior windshield surface above the dewpoint of the cabin atmosphere, WELL above that dewpoint, in the winter months.
 
With a significant portion of the WARM system airflow being cooled via flowing over a COLD windshield surface I seem to end up with a long term (greater than 15-20 minutes of travel time) setting of ~75F for a reasonable passenger comfort level.
 
Basically I find that the automatic mode goes TOO far in trying to not discomfort passengers with "overly" warm airflow and noisy blower speeds.
 
Using the above method I can both bring the cabin much more quickly to a comfortably warm level and prevent (mostly) those instances of sudden windshield fogging for which these systems are famous.

#128 of 174 Re: Weak Ventilation Fan [normkol] by sdc2

Feb 28, 2008 (7:52 am)

Replying to: normkol (Feb 26, 2008 6:16 pm)
The fan is not weak, the speed settings are just calibrated differently than you are used to. I think it is nice to have more choices at the lower speeds.

#129 of 174 Re: Weak Ventilation Fan [sdc2] by wwest

Feb 28, 2008 (11:21 am)

Replying to: sdc2 (Feb 28, 2008 7:52 am)
SDC2 is correct, most modern day systems now use PWM, Pulse Width Modulation, to control lower blower motor speeds, giving an infinite number of speeds vs the old dropping resistor(s) method.
 
That, of course, results in the system using those now available lower blower speeds in order improve dehumidification capability and reduce the cabin noise level. Once the cabin temperature, AIR temperature, is near or at your temperature setpoint during the winter months it doesn't take much make-up airflow to keep it there.
 
Additionally most new cars are extraordinarily well sealed against air outflow. The theory being that once the cabin atmosphere is "conditioned" then don't let it "escape".
 
The fallacy in that design approach, addressing only the issue of cabin air temperature, is that the human body comfort equation is as much due to radiant heating, or lack thereof, as it is to surrounding air temperature.
 
You might be entirely comfortable at ~70F in the interior of your home on the coldest day of winter with all the "surround" already heated to that 70F level. But now move yourself nearby a large picture window wherein a good portion of your body's "surrounding" landscape is snow and ice covered and you will undoubtedly begin to feel chilled.
 
In your car you cannot "escape" the radiant cooling effects of the surrounding snow or ice covered, or even just COLD, landscape so that otherwise normal 70F temperature setpoint will leave you COLD.
 
On a day, or night, traveling with a COLD outside landscape, raise the setpoint to something more in the range of 75F and change the system outflow to combined footwell and windshield airflow. The "warmish" airflow to the COLD windshield will be somewhat cooled before it reaches your face and upper body.
 
Personally I have ALWAYS disabled my A/C compressor during the winter months and now that these new systems are so potentially HAZARDOUS if left in operation I am carefull to NEVER allow the A/C to operate during cold weather.
 
Thankfully Toyota and Lexus, via new c-best options, have made it much easier to accomplish that rather than getting under the hood to disconnect the A/C compressor clutch wire.

#130 of 174 Re: Weak Ventilation Fan [wwest] by tidester

Feb 28, 2008 (11:47 am)

Replying to: wwest (Feb 28, 2008 11:21 am)
as much due to radiant heating, or lack thereof, as it is to surrounding air temperature.
 
They are not unrelated. When you move yourself over to the large picture window the air temperature is lower.
 
tidester, host
SUVs and Smart Shopper

#131 of 174 Re: Weak Ventilation Fan [tidester] by wwest

Feb 28, 2008 (8:17 pm)

Replying to: tidester (Feb 28, 2008 11:47 am)
Yes, there will undoubtedly, be cold air flowing downward off of the cold window surface. But my point is that the COLD outside surrounding landscape, unlike an interior room with no windows, will adversely contribute to human comfort.
 
I could put you in an atmosphere of 72F airflow, fully surrounding 72F airflow, but surrounded by blocks of ice, and the net result would be that you feel chilled.

#132 of 174 Re: Weak Ventilation Fan [wwest] by tidester

Feb 28, 2008 (10:37 pm)

Replying to: wwest (Feb 28, 2008 8:17 pm)
I could put you in an atmosphere of 72F airflow, fully surrounding 72F airflow, but surrounded by blocks of ice, and the net result would be that you feel chilled.
 
Obviously. But thermodynamics dictates that the ice will cool the air. The 72 °F airflow simply cannot remain a 72 °F airflow. The same happens to the air when it loses thermal energy due to radiation. However you want to pick the nits, yes, the total environment does affect your comfort.
 
tidester, host
SUVs and Smart Shopper

#133 of 174 Re: Weak Ventilation Fan [wwest] by normkol

Feb 29, 2008 (7:01 am)

Replying to: wwest (Feb 28, 2008 11:21 am)
What you're saying seems to refer to climate control. I'm talking about manual control.
 
Are you saying that the speeds on the fan control are not fixed, that there is some logic to them?

#134 of 174 Re: Weak Ventilation Fan [normkol] by sdc2

Feb 29, 2008 (8:20 am)

Replying to: normkol (Feb 29, 2008 7:01 am)
I have the base model and the speeds are fixed...but there are 5 speeds instead of the 4 all my previous vehicles have had. I do find myself using 2 a lot instead of 1 like I used to...but I have only had short trips so far and this cold winter has me wanting to heat up the cabin quickly. On a longer trips I expect I will drop to 1 once things are warmed up...heading out of town tonight so we'll see.
 
But if you turn the fan to the highest setting, I think you will see the fan is just a powerful as any other.

Messages Page 14 of 18

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