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Toyota Highlander Heating Ventilation and Air Conditioning

107 messages,  Last post on Nov 16, 2009 at 5:13 PM

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What is this discussion about? Toyota Highlander, SUV


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#40 of 107
Intermittent A/C Problem by luckybelly
Jun 28, 2008 (5:12 pm)
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I got 01 Highlander V6 with non-auto temp control.
My A/C is fully charged but intermittently I don't get cold air. I know this cuz I have used temp guage and know the temp when cold and warm. The temp setting knob works fine. But do not get cold air, while driving intermittently it will start sending cold air but consistently.
Anyone run into this problem and know the fix. Any help is helpful.
 
#41 of 107
Re: EZ Airconditioner fix [vdeam] by nimrod99
Jun 28, 2008 (7:05 pm)
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Replying to: vdeam (May 16, 2008 6:13 pm)

Dublin Toyota service / dealership are crooks
never take your vehicle there. I would say 90% of dealerships are crooked
#42 of 107
Re: Intermittent A/C Problem [luckybelly] by wwest
Jun 29, 2008 (6:40 am)
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Replying to: luckybelly (Jun 28, 2008 5:12 pm)

If the engine coolant is approaching the level of overheating, not yet at that level, the A/C will be shut off to keep the condensor from pre-heating the airflow to the radiator. Once the coolant temperature drops back to the normal range the A/C will start up again.
 
Being stopped for awhile or moving slowly along in stop and go traffic with the engine mostly idling and A/C still going on a hot day will result...
#43 of 107
Re: Intermittent A/C Problem [wwest] by luckybelly
Jun 29, 2008 (4:43 pm)
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Replying to: wwest (Jun 29, 2008 6:40 am)

Coolant temp guage shows normal temp.This happens while driving at normal highway speed and on streets. It intermittently works fine and then it doesn't.
Are there sensors that prevent it from turning on?
#44 of 107
2008 Toyota Highlander A/C by khenkel
Jul 18, 2008 (9:04 pm)
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Here in the Las Vegas summer heat the A/C doesn't get the vehicle to cool as quickly as expected (+20 minutes).
 
Has anyone else had similar problems?
#45 of 107
Re: 2008 Toyota Highlander A/C [khenkel] by grahampeters
Jul 19, 2008 (12:13 am)
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Replying to: khenkel (Jul 18, 2008 9:04 pm)

G'day
 
I'd take it to the dealer as it has probably lost some gas. The Air Con is super efficient and copes well with Australian summers (similar to Nevada) so there sounds to be something not wrking correctly
 
Cheers
 
Graham
#46 of 107
Re: 2008 Toyota Highlander A/C [khenkel] by wwest
Jul 19, 2008 (8:26 am)
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Replying to: khenkel (Jul 18, 2008 9:04 pm)

The human comfort equation involves air temperature, humidity, and radiant heating/(cooling) effects. If you let the car set out in bright sunlight with the windows rolled up the interior will (over)heat to such a great level that it might take an hour with a dark or black interior for the A/C to cool the interior surfaces enough that their radiant heating effects on your body can be overcome by the A/C cooling airflow.
 
There are times when Toyota's design engineers seem to be a little TOO concerned with passenger discomfort and "this" is undoubtedly one of those times. You can be cool the cabin down quickly by discomforting yourself briefly with system airflow that is a bit TOO cool.
 
First, move the temperature setpoint to the COLDEST position. That should result in the blower speed going to the highest level once the A/C begins cooling the airflow. It will also, typically, result in the system switching to recirculate mode. If so then immediately switch it back into fresh mode and lower the rear windows an inch or so.
 
The object of this "stage" is to move the "super-heated" airflow out of the passenger cabin and in the process hopefully reduce the interior surface temperatures slightly.
 
Over time and trials you will begin to be able to judge when to switch to the next stage.
 
Now switch the system to recirculate mode and lower the blower speed to adjust your noise intrusion comfort level. At this point the lower the blower speed is the lower will be the temperature of the system airflow. If you continue to need it cold, TOO COLD, in order to more quickly cool down the cabin then you might want to switch the airflow to footwell or mixed dash/footwell mode.
 
I found it helped quite a bit cooling wise, COOLDOWN, to purchase and install a manual water flow shutoff valve in the engine coolant flow line to the heater core. That not only serves to bypass the reheat.remix mode of the HVAC system but results in a significantly lighter load for the A/C compressor and thereby an improvement in FE.
#47 of 107
by kenlw
Jul 19, 2008 (4:51 pm)
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Not to disagree but the heater bypass valve should already be closed (actually, in bypass mode) when the temp is on "cool" and the outlets are not on defrost.
 
To cool a car down quickly after sitting in the sun, 1st put down ALL the windows, switch the AC to NON-recirculate and the highest fan speed. After about 1-3 minutes of driving, roll up the windows and switch the AC to RECIRCULATE.
 
Why? The fastest way to move the cabin temp down from 140 is to get it to 100 by rolling down the windows. Then let the AC take it from 100, instead of trying to make it work against 140 air.
#48 of 107
Re: [kenlw] by wwest
Jul 20, 2008 (7:13 am)
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Replying to: kenlw (Jul 19, 2008 4:51 pm)

"heater bypass valve should already be closed..."'
 
If you mean the reheat/remix vane/door then it will only be fully closed, and REMAIN fully closed, with the system in the max cooling position. On the other hand if you mean the actual coolant flow valve then the beancounters have been successful in eliminating that feature some years ago now.
 
If the hot engine coolant is allowed to flow through the heater core then the radiant heating effects can be rather substantially adverse to the cooling capability of the system.
#49 of 107
Re: Intermittent A/C Problem [luckybelly] by tonney
Aug 01, 2008 (5:34 pm)
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Replying to: luckybelly (Jun 28, 2008 5:12 pm)

My 03 Highlander has a similar problem. When either the fan/vent or A/C is on, every once in a while the heat starts blasting. Very inconvenient. Had this diagnosed today - a resistor in the circuit board behind the panel will have to be replaced...$1,100!!!!
 
Anything like this out there???

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