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Highlander Hybrid Air Conditioning Questions

20 messages,  Last post on Jun 29, 2010 at 5:22 AM

You are in the Toyota Highlander Hybrid Maintenance & Repair Forum.

What is this discussion about? Toyota Highlander Hybrid, Heating / Cooling, SUV

Messages Page 2 of 2

#11 of 20 Re: AC Indicator Light w/NAV [bob2006] by cdptrap

Mar 10, 2006 (6:11 pm)

Replying to: bob2006 (Mar 10, 2006 4:28 pm)
Hi Bob2006,
 
Geeting snow in "sunny" San Diego today? Strange weather in Northern CA so far, 3-inches of snow around our place and our HH has gone through sleet, hale and snow today and last night, fourth time this season. More tonight, tomorrow and tomorrow night.
 
Drive safe.

#12 of 20 Important HVAC custom parameters by wwest

Mar 18, 2006 (1:12 pm)

The RX400h and HH have several custom setup parameters which owners should be aware.
 
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 in a reoccurance of windshield 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 the sun's radiant heating effects. The human comfort equation is much more complex than can be resolved 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 this 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 chooses 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?

#13 of 20 Re: Important HVAC custom parameters [wwest] by discussion1

Mar 19, 2006 (10:17 pm)

Replying to: wwest (Mar 18, 2006 1:12 pm)
Can you put it in less technical terms? Such as what I must do?
 
Our experience is when defroster is ON, the blower goes high and blows hard until we shut off. It clears everything quickly.
 
On cold days, with outside temperature at low 30's, internal breath will slowly fog up the windshield. We manually set temperature to warm and select vent+floor and run the fan low or 1. This keeps the windshield clear and interior comfortable.

#14 of 20 Re: Important HVAC custom parameters [discussion1] by wwest

Mar 20, 2006 (10:30 am)

Replying to: discussion1 (Mar 19, 2006 10:17 pm)
Sorry, I didn't explain very clearly.
 
Until the cabin has warmed to a level at least close to your temperature setpoint it is very typical for the blower speed to increase, even dramatically if the cabin is really cold.
 
Once the cabin has warmed to the point wherein it will begin the sequence of automatically re-routing outflow air from the footwell to mixed and then to dash only there will be very little or not reaction to switching to defrost/defog/demist mode.
 
The custom parameter setting would/will result in the blower speed rising when you activate defrost/defog/demist mode regardless of cabin temperature.
 
During the winter months you can help to prevent inadvertent windshield fogging by being sure the A/C compressor is NEVER used and by being sure to keep the system's air outflow mode in footwell ONLY.

#15 of 20 Musty or mildew smell from a/c? by larry70

Jul 13, 2007 (11:01 am)

AI have had my HiHi for 1 1/2 years. Now,there is a musty smell inside that is not caused by the carpet or mats ever being wet. When the a/c is turned on, for the first blast of air, it smells. The dealer changed all the filters, with no solution.
Anyone else have this problem? Maybe the a/c line is clogged or something.
Larry

#16 of 20 mildew smell by larry70

Jul 13, 2007 (11:33 am)

The braking question was not supposed to be mixed with the mildew question, but I messed it up.
 
CDTRAP - you are exactly correct on all your descriptions of the braking issue. I am hoping it is not a safety issue.
 
On the musty smell, the dealer's service writer was the only person of 3 of us who could not smell it. The dealer doesn't have a clue, other than to charge me $85 to replace the filters that didn't seem that dirty to me, but then, I am only a dumb car owner.

#17 of 20 air conditioner filter by hidesertdi

May 25, 2010 (1:26 pm)

How often is it recommended to have the air conditioner filter checked? Is that part of the maintenance of an oil change at the dealerships? We're smelling something like a dead animal from our engine area. We cannot see any critters in grill or otherwise. When I check my air conditioner air filter today, it was overflowing with all sorts of debris. I know for a fact it was changed last year and I just had my oil changed at a dealership a couple of weeks ago (that's why I was wondering if they check the filter at oil change). Has any body else had problems with dead animal smells?
thanks for your time!

#18 of 20 Re: air conditioner filter [hidesertdi] by monte8

May 26, 2010 (9:38 pm)

Replying to: hidesertdi (May 25, 2010 1:26 pm)
I have not had the problem, but if you live in (or drive through) an area with large concentrations of flying insects, they could end up in the cabin air filter. Some insects really stink. Around here (prairie pothole region of North Dakota) we have "fish flies". These will turn the front end of your car almost black (it looks like your car has a 3 day old beard) in minutes. And it smells bad.

#19 of 20 Re: air conditioner filter [hidesertdi] by wwest

May 27, 2010 (7:33 am)

Replying to: hidesertdi (May 25, 2010 1:26 pm)
Living out in the woods as we do I have had mice, and squirrels, build nests in many of our cars over the years. It is not at all unusual to find a dead mouse somewhere in the HVAC fresh air intake system/path. The most common entry point seems to be around the windshield wiper shaft where it comes up through the cover just below teh bottom of the windshield.
 
To inspect for a dead animal you must remove that cover and then probe blindly into some of the recesses, especially the fresh air entry recess, you find there. Remove any nesting material you find there.

#20 of 20 Wet Floor Mats in Front - AC Problem? by CTKaren

Jun 29, 2010 (5:22 am)

My two front floor mats and base under mats are wet lately. I think it must be related to running the AC. Any ideas why this would occur or if there is anything I can do myself to avoid a repair bill? Maybe a filter clogged from tree debris?
Toytota Highlander Hybrid 2008

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