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Discussion Starter · #1 ·
I have an '01 Tundra and one of things that bugs the hell out of me is the fact that I can't turn off the A/C independent of the defrost.

One of the reasons is that I don't like driving with the vents blowing air in my face so I like to drive with the vent in defrost position. Plus, there are days when you just need a little air on the windshield to defrost without the A/C.

I understand that the A/C de-humidifies the air and that's why it turns on with the defroster. But..... In my Acura and Honda you can turn the A/C off even with the defrost on. BTW...I don't want to pull the wire on the switch.

Can anyone with an '07 Tundra confirm this for me. Does it come on and stay on with the defrost? Can you turn it off even thought the vent is in the defrost position?

Thanks - Teg
 

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I think ALL vehicles use the A/C with defrost these days. The reason is to dry the air. By sucking the moisture out of the air it can defrost the windows faster.
 

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Discussion Starter · #3 ·
I think ALL vehicles use the A/C with defrost these days. The reason is to dry the air. By sucking the moisture out of the air it can defrost the windows faster.

Yes, but SOME allow you to turn off the A/C while it is in the defrost position.
Since you own an '07, can you tell me if you can turn off your A/C while it is in the defrost position. Not just the light, but the A/C system. (on earlier models, the A/C stays on even though the light is off)
 

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You know there's an easy mod to diable the a/c when any of the defrost mode is selected. Just take off the control panel and on the knob selector is a plug that turns on the a/c, you unplug that. After that, the a/c will turn on only if you push the a/c button, even in defrost mode.
 

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Yes, but SOME allow you to turn off the A/C while it is in the defrost position.
Since you own an '07, can you tell me if you can turn off your A/C while it is in the defrost position. Not just the light, but the A/C system. (on earlier models, the A/C stays on even though the light is off)
I believe this is true with the 07 as well. The only way I know you could do it would be to a) pull the air compressor fuse b) pull the connector plug off the compressor itself.

My question is why are you so concerned with turning it off? I don't think you will see any appreciable performance or mileage gain if you could turn it off.
 

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The light does not go on, but the AC does turn on when you select the defrost.
 

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You know there's an easy mod to diable the a/c when any of the defrost mode is selected. Just take off the control panel and on the knob selector is a plug that turns on the a/c, you unplug that. After that, the a/c will turn on only if you push the a/c button, even in defrost mode.
What does this accomplish besides lengthening the defrost times? What is the upside to disabling the A/C portion of the defroster?
 

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What does this accomplish besides lengthening the defrost times? What is the upside to disabling the A/C portion of the defroster?
The upside is after the mod it starts to blow heat faster. AC during defrost does nothing for melting ice/frost on my windshield, and in fact slows it down. I pulled the plug off the micro switch on the back side of the defrost control on both my Tundra's, issue fixed. Toyo should at least give the option of being able to disable the AC like Honda does.
 

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The upside is after the mod it starts to blow heat faster. AC during defrost does nothing for melting ice/frost on my windshield, and in fact slows it down. I pulled the plug off the micro switch on the back side of the defrost control on both my Tundra's, issue fixed. Toyo should at least give the option of being able to disable the AC like Honda does.
When you run the defroster to clean the fog from the inside of the windshield, having the a/c compressor running sucks the moisture right out of the cabin and freezes it on the evaporator. Conversely, when you turn off the defroster and go back to heat on the floor etc, the a/c evaporator defrosts and then you have the fog on the windsheild again due to the high humidity. I prefer to be able to control the a/c compressor like Honda or Acura allows. I don't want the a/c to activate because I switched on the defroster.
 

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Turn the temp knob up to hot. The aluminum block heats up pretty fast. I noticed the temp guage moving up before I get out of my neighborhood. The defroster does use the ac to evaporate the air moisture but it also cycles just like the main ac control. The warmer you have the inside temp set the less the ac is used. To be honest, I've played with the ac on and off at stop lights and I can't feel it kick in or out. No change to the RPM's. This 5.7 is a brute.
 

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Discussion Starter · #11 ·
I believe this is true with the 07 as well. The only way I know you could do it would be to a) pull the air compressor fuse b) pull the connector plug off the compressor itself.

My question is why are you so concerned with turning it off? I don't think you will see any appreciable performance or mileage gain if you could turn it off.
You don't think that you get better mileage with your A/C off -vs- on?:confused:
 

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What does this accomplish besides lengthening the defrost times? What is the upside to disabling the A/C portion of the defroster?
I like having warm air blow through the windshield vents and floor vents in the winter, even though there's no fogging on the windshield so I want the a/c to be off. Also the area where I live, it's not very humid even in the winter time. If there's any fogging, it usually disappears after a few minutes of warm air even with no a/c on. Also with no a/c on, you don't get the engine surging when it cycles on and off. Lastly, that's how my Honda and Mazda use to work and I want the Toyota to work the same way!
 

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:confused: The air will still be warm as long as you have the temp selected to hot. It just acts as a drier.
 

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There I was, looking through the gaggle of documentation and other interesting Tundra stuff I'm collecting in preparation for the major purchase.
The file is called "Changeable Tundra Electronics.pdf", which I downloaded from this site some time ago, or maybe from the other Tundra Site I frequent. This is the same file referenced in the long ago thread from a Tundra owner who wanted to disable a seat belt buzzer.
I have a copy of the pdf file so the custom settings I want will be part of the deal, and I won't have to pay Toyota service charges to change something that THE VEHICLE OWNER SHOULD BE ABLE TO DO!!
Oops. Sorry.

Anyway -
On page 1 of this pdf (page IN-20 in the service manual it was copied from), there is a setting called [FONT=&quot]"COMPRS/DEF OPER,"[/FONT] changeable with someting called an Intelligent Tester.[FONT=&quot]
[/FONT] Its description is: [FONT=&quot]"Function to turn the A/C ON automatically linked with the FRONT DEF button when A/C is OFF."
[/FONT] The choices are: [FONT=&quot]MANUAL / LINK
[/FONT] The default setting is [FONT=&quot]LINK.[/FONT]

If this is what you're looking for, a trip to the Toyota service dept can tell you if this can be set to [FONT=&quot]MANUAL[/FONT] for you.
But it may cost.
 

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StevJ,

Nice find, I didn't even think to look at that. You are a smart man!!!

Here is the file again for you new guys.
 

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Discussion Starter · #19 ·
I can turn the AC off in mine when one defrost, at least the light turns off...

Yeah, the light turns off on mine too, but the A/C is still on:td: You can hear and feel it cycle. It also leaves a water spot on the ground from condensation.
 

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If it is pulling water from the air it is decreasing your defog time. Again, is there a major advantage that I'm not seeing?
 
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