Disable AC in Defrost Mode

At times I'd like to have air blowing on the windshield, but not have the AC compressor kick on.
I was able to mod my 2002 4Runner to do this, and I see online tutorials for doing it on a Tacoma. Anyone done it on Tundra?

 

No, but I'm interested in this as well. If i have a little time today I will hit the wiring diagrams and see if i can find out.

 

Me too

 

Unplug the connector at the compressor.

 

I'm lost. Pretty sure I can blow air on my windshield without the compressor being on.

 

I'm curious...what will this gain you?

 

You can't. The ac automatically comes on any time you are on defrost or defrost mix. It does help a lot with defrosting, turning the AC used to be a 'trick' with cars to clear the windshield faster...but the tundra does it without asking.

 

That would kill all AC, we just want to kill it automatically coming on with the defrost setting.

A lower idle speed in winter. Less wear and tear on the compressor. Probably a little gasoline.

 

But the compressor has its own stand alone button. If it's off I didn't think the compressor would kick on.

Maybe I'm not understanding what you guys are calling defrost.

 

Nope. In defrost it'll run regardless of the independent A/C switch. I don't think any vehicle made in the last 20 years doesn't do the same.

 

Yeah, defrost is tied into the compressor to dehumidify the air. It greatly improves the defrost capability.

 

So by turning the vents to blow on the windshield my compressor automatically kicks on? I never noticed. Typically hear the change in RPM.

In other vehicles I've owned the light for the AC would kick on automatically and wouldn't allow you to turn it off. The tundra doesn't do that. I learn something new here everyday.

 

Are you guys talking about the defrost button on some consoles (sorta bottom right button)?
I don’t have that button, but if I just turn the selector knob to either defrost position and have the fan on my a/c doesn’t come on, unless recirculate is on, then a/c comes on.
Most vehicles I’ve had run the a/c if recirculate is on.
At least that’s what I’ve observed, haven’t double checked since seeing this thread, will check tomorrow... maybe I just didn’t notice?

 

That's what I thought too. But they are claiming the compressor comes on when you move the vent flow to windshield, even though the AC button isn't pushed.

 

Nope, we are talking about the vent position. Set to defrost or defrost/floor mix, the AC compressor will cycle on and off automatically with no way to turn it off. I bought my truck in the winter and I first thought it had an engine problem because at idle every 30 seconds or so the the engine RPM would surge slightly, but then I watched it with the hood up and figured out what was happening.

 

I can't help but notice my ac comes on when I use defrost because it plays with my idle from time to time sitting at stop lights. It will idle down slowly and then jump up a bit and if my foot isn't firmly planted on the brake it will do a slight lunge forward. Very annoying.

 

Yes. That exactly.

Its annoying too because during the winter I basically set the vent on def/floor mix and never change it, but I really don't feel that I need AC all the time. My old truck didn't even have AC and vent was always enough once the engine was warm.

 

Yeah I do the same. If I put it all on the floor for some reason my face gets hot and my feet get cold. If I'm using def/ floor mix it's about right. Don't get me started on our crazy Toyota vents. Freaking rear vents blow cold in the winter and warm in the summer. What's the point of that? Save money and throw it out the back of the console. I might have to do that mod one day.

 

For what its worth....

You will see that there are two different wires for the AC clutch, I wonder if one of them happens to be the defrost override....

 

Unplug the electrical connector on the vent position control. I think that's all you need to do.

 

That's what I'm talking about!

Your Google-fu is strong Bubba! I searched before I started this thread, but came up dry.

Thanks!

 

Thanks but that is one of many links I have saved from tundrasoultions from before I found the Truck Gang site
Now that I have the cluster still off from yesterday in working on cig light, may look at trying that suggestion even tho this issue does not bother me giving our environment and lack of not using the F/DEF position very often.

 

I tested this morning and you guys were right. I had never noticed the compressor kicking on before when moving the vent to windshield. That's a bummer.

 

I can see the argument for a disable mod for some, but once its disabled then its not there when you need it. Its nice having the defrost mode direct blast right on the shield vs using reg A/C mode to clear the glass which takes much longer.

Also, I like the defrost option during those St Bart summer months. Keeps the frontal air action moving instead of direct out of main vents blow.

Before fixing all my interior cab water leaks I would use defrost mode more often due to introduced humidity. Now its almost like Arizona inside.

One last tip: Its good to run your A/C in the winter on an occasional basis. Reason is that the freon has oils that need circulating to lubricate and condition the inner seals. Same thing with your home A/C system.

 

Press the A/C button and it will re-engage the air conditioning, blowing it once again onto the windshield.

All disconnecting the switch does is prevent the a/c compressor from always being engaged when defrost is on. It doesn't prevent it from ever being engaged when the defroster is selected.

 

I gotcha.

 

But will the ‘A/C button on light’ illuminate when the dial is switched to ‘defrost’? Post mod?

Today was the perfect day for me for the defrost option in our trucks. Rainy with wet shoes and clothes along with 2 passengers fogging things up, the dial was turned to defrost all day with the temp dial on medium heat. Very comfy.

Right now the A/C button does not light up when in defrost (dialed). You can make the A/C light up if you push the button though.

Just a little nuance.

 

Indeed. It works well. We just want control over it, especially in places where that is the climate control setting for nine months of the year.

I will disconnect the dial switch wires tonight and should know right away if it has any effect on normal AC operation.

 

I too ‘tested’ this today, just tried switching it on and off while parked at idle, and it did change my idle, which is presumably the compressor kicking on (I couldn’t hear the compressor or feel cold air, since the air was already cold).
I guess if it didn’t bother me before it won’t now.
Other than maybe dragging milage down a little (maybe?), it does seem to function well for clearing the windshield in my wet truck, and should help maintain the a/c.
Funny thing is, I would never use my a/c otherwise, I never need it in summer.
This post is of no help to the op, but thanks for teaching me something new about my truck