Hello again 4runner gods,
A couple months ago I noticed my gas level dropped quite a bit. I chalked it up to my broken Air for Fuel Air mixture sensor, which has been causing my gauge cluster to turn all kinds of lovely orange, and added the parts to my Christmas list.
About a week later I started to notice that the air coming through the vents was considerably colder than the ambient outside air, I had the windows open because Florida. I checked to make sure the A/C light was off, and it was. After I got to my destination I went to do some things, came back, and noticed there was a nice little puddle on the ground where the A/C condensation would normally go.
In other words, I'm pretty sure my A/C is stuck in the on mode somehow, and I haven't the slightest idea on what to do to turn it off. So far I have tried turning it off and on again, disconnecting the battery (well, technically the battery died and I had to swap it, but close enough), and checked the fuses. And still puddles of condensation fluid.
Any ideas?

May be you have a stuck AC switch? But if it is stuck your blower fan should turn it off. What year is your truck?

Are your rear controls turned on? On the backside of the center console there are controls that people sometimes forget about.

It's a 2002. It could be the switch for all I know. I haven't tried going for a drive with the HVAC all the way off, I tend to leave it on low with ambient air flowing through it. I'll leave it off for the drive home and see if that stops the puddle .

And I just checked the rear controls, looks like it's in the off position from what I can tell.

The A/C IS always on, to some degree, if the HVAC is running at all as a dehumidifier. The only way to stop it is turn off the HVAC altogether or wire in a cheat switch to the compressor clutch. If you leave the fan off and recirc off, you will still get some outside air while moving with no A/C.

In Florida humidity, it doesn't make much to leave a puddle.

Rear controls would make no difference; that's just heat.

My AC only turns on when defrost is being ran.

So my magical "Hey, this is why my gas milage is terrible!" excuse is gone. Bummer. Oh well. thanks for the tip, I didn't know that. I thought that "A/C light off = No A/C".

Well, I checked a little more. On manual A/C systems, the above poster is correct, the A/C only functions in defrost and mixed defrost/cabin mode. If you are using one of these, try the others.

Not sure about the digital.

Mixed cabin mode also shuts AC off. The AC light will turn on when in the defrost only, not mix. At least on the older HVAC models.

I was having the same issue on my 2002 and couldn't figure it out. Then I realized someone had turned on the air in the rear. Turned it off and it stopped. But if it's already off on your's then I'm not sure....

There is no rear air on my 2000 just rear heat , are 2002 different ?

I only have rear heat in my 02 also.

yea i don't think any 3rd gen has air in the back

Only heat in the rear. I thought it was my AC because I could constantly hear the blower running, didn't check for a water puddle

For my 99 with rear heat, it's a little confusing because the lever that controls the temp has a blue to red indicator so you think it cold for a/c. Also, for the fan to be off the switch has to be in the center neutral position, not triggered up or down.

Up or down is just the hi/low of the fan.