Disable AC While Defroster On
 

Howdy all,
I have seen ways to disable AC from automatically turning on in the Defroster setting, but only for 4th gen and up.
Does anybody know how to do this mod on a 3rd? I pulled out the climate control unit and didn't see the the connecter that people are saying to disconnect on 4th gens. Can this be done on 3rd gens?

There are different versions of the climate controls on the 3rd gen. On the manual controls found on the '96-'00 base and SR5 models, it is very easy (unplug a connector, as shown in the link above).

The Limiteds that have the auto-ac setup is different and probably not that simple. You may have to put in an AC disable switch that disables AC in all settings (disconnecting the control wire to the AC compressor relay).

-Charlie

I have a 99 limited and when I push the defrost only button the A/C button lights up, but I just simply push the a/c button and it shuts the compressor off. I’m not sure if that’s the same on the SR5 dials, but other vehicles that I had in the past with the compressor turning on when putting on defrost only, I would use the feet/defrost setting so the compressor won’t turn on.


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This seems to be as good an opportunity and place as any to ask about an odd but very minor difference between Base and SR5 4Runners.

We own two Base models, a '99 and a 2000, and a 2000 SR5. (Three 4Runners, fourteen cylinders, all 4wd, all five speeds.)

Anyway, on the SR5, engaging the defroster does indeed engage the AC, and the little light on the AC switch is automatically turned on.

On both Base models, however, engaging the defroster also engages the AC (verified by the tach and by visual inspection of the AC's clutch), but on both of them the little light on the AC switch does not light!

Any other Base owners notice this? If it were just one of them doing this I'd suspect an electrical fault. But with both doing it? (Yes, the little light does come on when the AC button is pushed.)

It's no big thing, just a curiosity. Likely just a minor difference in the code in the chassis computer.

The AC light should stay off in defrost mode (for both base and SR5 models, '96-'00) even though the AC system is turned on. There is a diode in there that keeps the light off but still triggers the AC amplifier to be active. I'm surprised the '00 SR5 does turn on the AC light... Does it still use the lever style controls of your base model trucks? In '01, the SR5's (no more base model) used semi-electronic controls that might act differently.

-Charlie

Identical HVAC panels across all 3 of our vehicles.

Maybe it's my SR5 that has the problem - a faulty diode, perhaps - and the Base models are working as designed. I hadn't considered this.