A/C kick ON, once Defrost is ON!

Tacoma 2002 - Pre-Runner
2WD - 4 Cylinder


Hi, I would like to know how to disable the A/C from coming ON when selected the mixed(floor/windshield) and windshield only modes on the environmental selector. Basically the A/C get on even the A/C button is OFF. I do not need to A/C on once i use the Defrost. It save a lot of the MPG.

I found the great instruction to change the wires from D3 connector triggered the A/C amplifier to engage the compressor for second generation of Tacoma.
https://www.tacomaworld.com/threads/a-c-on-with-defrost.7160/

This is another way:
https://www.tacomaworld.com/threads/defrost-without-a-c-mod.126495/


I would like to know if it's going to work for first generation too!

TNX

 

Yes it’s correct that the defroster uses air from the ac as the air has a dried affect and help to defog or defrost the windshied. This means that if the defrost is on the the ac compressor is on.

 

Yes, But have you try to disable the A/C once on Defrost?
Do you think this way is going to work?
https://www.tacomaworld.com/threads/defrost-without-a-c-mod.126495/

 

Ac works by dehumidifying Before cooling.

So when you want to defrost the ac kicks on to help dehumidify

 

Why would you want to blow warm moist air on the inside of the windshield. If you don't want cold air set the temperature dial somewhere in the middle then you can blow dry air that is anywhere between hot and cold. The key is dry air. Not using the AC with the defrost on would make things worse.

 

Help. My wheels keep going around in circles when i drive....

In other words, is working as designed.

 

While most modern vehicles kick the ac on during defrost, Defrost does, and has worked for a billion years without ac.

 

There is a thread in this forum on the mod. If I remember correctly, you modify the stop on the mode selector so it can go one position past defrost. The result is defrost with no A/C. I want to do this mod because it would have a positive effect in my climate. In the winter it is usually low 40's or high 30's and somewhat dry. Engaging the defrost with the A/C on actually makes the fogging worse before the engine produces some heat.

 

It's okay if it's winter and you just want to heat up the windshield tho

 

This is the fastest way. I did it though I never use it due to the bad effect in rain. I need the AC-linked defrost here. All you do is take the selector knob off, shave off the square stop-tab on the underside of it, then replace it back on. You can now move the selector that one notch past defrost where it'll blow non-AC-linked defrost air.

 

On my 1999, there is a 2 pin connector near the defrost knob. If you disconnect it, you will get the exact functionality you are looking for. And it’s easily reversible!

 

@akrinar, I highly doubt you'd notice a difference in MPGs with the A/C on...

That's not really true.

If you have the temp dial set on med/high, it's not cooling the air (thereby making the fogging worse) or doing anything different than if the a/c was off, aside from dehumidifying the air. It's just pulling ambient temp air, which, if your windows are fogged, is cold air.

 

Perhaps I was imprecise. This issue only occurs immediately after startup before the engine is pumping hot coolant through the heater core. When I drove my 93 F150 that does not engage A/C on defrost I had basically no issue. When I drove my 98 Camry in the exact same condition, the window fogging would get so bad that I couldn't see. On occasion I had to pull over to the side for a couple of minutes so the engine could supply hot coolant and the defrost would function.

The issue is the cold air coming out of the defrost vents cooling the glass and causing condensation. Sure operating the wipers can clear it, but not cooling the glass fixes it too.

It is a narrow use case which only lasts about two minutes, but I does exist and I'm able to repeat it. I've not driven my Tacoma in this condition yet, but I will in the next few months.

 

Like I said, even with the A/C on, you're not pumping cold air unless you have the temp set to low. Turn the heat up and it will blow hot air (once the engine has warmed up a bit).

When it's cold (in CA I use that term loosely, lol), I usually let my truck warm up for those 2 minutes anyway.

 

Unplug the wire off the front of the compressor. No more ac with the defrost or without.

 

It's not about warm/cold air at all!
If you switch to the defrost, the Compressor will kick ON and starting to engage in earlier Tacoma models. The whole point is I do not want to engage and run with A/C compressor once I'm using the Defrost. It's made a lot of difference in RPM and MPG's once the car run with A/C compressor. As I said it's nothing to do with Cold/medium/HOT air..

Thanks

 

That's the last option...
Tnx

 

True...

 

Yes, It's in earlier Tacoma models. Nowadays you have the option to keep A/C On or Off once the Defrost is ON.

 

You do not get it Bro!!!
Yes, it designed that way. But we are going to change it...