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#1
10-27-2003, 12:12 PM
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Window Fogging
Every Toyota I've ever owned has had this problem; 92 4X4, 91 Celica GT, 94 4Runner... if it is raining... the AC is on, no problem. If not, everything fogs. The AC needs recharging in the 4Runner and will only work for a few minutes. Has anyone found a way to keep the windows from fogging, without the AC? Thanx.
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#2
10-30-2003, 02:01 PM
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make sure that the climate control that controls where the car is getting air from is in the position that shows the arrow coming throught the window....make sense?
 it only has two settings one picture shows the arrow circling the inside of the car, the other shows the arrow coming through the windshield. If that doesnt help the fogging, then you might just have to crack open a window....
__________________
1997 Toyota 4Runner Limited Built ZC in 90 Civic std model....  as marked001 says Don't click here
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#3
11-13-2003, 01:27 AM
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Hey lost in the fog,
I find keeping my window really clean helps. Like one a month Windex stuff clean. Any window cleaner will work, just be careful not to be "overly" aggessive when cleaning the rear window with the defrost wires.....expensive mistake. Fog-X is a pretty good product to...just make sure you use a clean terry towel. I am currently seeing if I can increase airflow in the back of my 4Runner with a computer fan taped over the vent....I just do not think there is enough flow through with these rigs. Wish me luck...if it works I will post my results on this site to tell all how to do...... 
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#5
03-02-2004, 03:28 PM
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Re: Window Fogging
Quote:
First, the A/C cooling evaporator, heat exchanger, was made a lot more dense and complex. The more chilled surface area for the air to flow over, the higher will be the efficiency of the heat transfer. The second issue is more directly pertinent to your problem. The slower the air flows over the evaporator's cooling surfaces the more it will be cooled and the more it is cooled raises the likihood that it will be simultaneously DEHUMIDIFIED. Another benefit of the lowering of the incoming airflow rate is better MPG, something I'm sure the automotive manufaturers haven't over-looked. Almost all modern day passenger vehicles are very well sealed against atmospheric outflow for these reasons. The way NipponDenso has chosed to keep the evaporator airflow as low as possible is by restricting the cabin atmosphere OUTFLOW. The result of that is that during the cooler months it will be really easy for the passenger cabin to become extremely humid, so humid that the windows and windshield interior surfaces, cooled continously by exposure to COLD outside atmosphere, begin to fog over. My suggestions... If it is possible to completely disable the A/C during the winter months then do so. My 01 RX300 has C-best options which allowed the dealer to "unlink" the automatic operation of the A/C in both "normal" and defrost/defog/demist modes. ON a previous 92 LS400 I fooled the system into thinking the OAT was below 32F by adding a resistor in series with the OAT sensor. I have also, on occassion, simply disconnected the A/C compressor clutch electrical circuit. My 01 Porsche has a switch added within the glove box that does that. If you park the vehicle inside it will help to leave a window or windows open so the cabin can more completely dry out. During A/C operation the ~10,000 square inches (92 LS) of evaporator surface area will become saturated, clogged, with mositure and while much of that will drain away via the provided drain a lot will remain and then evaporate into the A/C plenum and thus into the passenger cabin at the first start of the system blower. My most common occurance of intermittent and spontaneous windshield fogging was about 5 miles into my morning trip to the office during the cooler months. That instance was cured, mostly, by leaving the windows slightly open during the night in the garage. Another instance is that the A/C compressor will oftentimes shut down spontaneously, without any indication to you, if the OAT declines to near or below freezing. A few minutes after that happens the condensed moisture remaining on the evaporator will begin to evaporate into the airflow entering the passenger cabin. Be VERY CAREFULL, this can be a very HAZARDOUS situation. If you are traveling in a colder climate and begin to see wisps of condensation on the interior surface of the windshield DO NOT ACTIVATE the defrost/demist/defog function before you turn the system heat all the way to MAX! Those wisps of condensation might be indicative of the A/C compressor having previously shut down due to low OAT and now if you activate the defrost/defog/demist function the COLD windshield will become suddenly opaque from condensation due to the moisture bomb building up with the A/C plenum. The best procedure to use if you sense that the humidity is to high within the passenger cabin is to lower the rear windows slightly and quickly purge the humid atmosphere from the cabin. While I remain a strong advocate of the use of A/C to dehumdify the incoming cabin airflow and thereby help to remove windshield condensation and prevent it's formation, I don't understand why, other than the slight discomfort one might feel, the defrost/defog/demist airflow isn't also HEATED. Wwith Outside Air Temperatures, OAT's, below about 55F it is impossible to predict whether or not the the A/C can be efficient enough to be of any help. The A/C's dehumidifcation efficiency is a function of the relative humdity of the incoming airflow. The lower the temperature of the incoming airflow the lower is the probability of efficient dehumdification by the A/C until at about 35F it is practically non-existent.
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