so I HAD a 2000 4runner and now ( very recent) a 2001. I noticed that with the heater fan switch off, and the heat control set to anything....the fan runs low. Even if fan control pointed to off. Its not a limited with the automatic heating system...its all turn knob stuff. It does shut off with key off.
Is this normal for a 2001 or 2002. maybe it was typical of the 2000 just dont remember

Check to see that you have recirculate turned on. If it's off it will blow some air from the outside. If it bothers you enough turn it to defrost mode so it doesn't blow in your face.

We are not as cold as Alaska but I don't like warm air blowing so I keep it on recirculation and have my rear heater going which makes it confortably warm.

+1 to what Zingvs said.

I thought the same thing with my 02. Why am I still getting air pushing through with everything off. It's was cause the recirculation was off and it was just air from outside coming in.

If the fan is indeed on and it's not just air being pushed through when the truck is moving it MIGHT be the blower motor resistor. Typically when it goes bad certain speeds stop blowing but maybe it could cause it to not stop blowing? I know this can happen with a radiator fan resistor if it gets a short.

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Maybe just a dial issue, out of sync or worn out contacts within the dial. I'm sure you didn't leave the rear heater on low by accident making the noise lol.

Check your rear heater. I've had this before only to realize I left it on. It's on the back of the center console near the cupholders for the rear seats if you have one. Like spartacus, I also keep it on in the winter as it keeps the interior warm without a hot hair dryer going in my face all the time.

not the recirc button, checked that after the posts above, makes no difference if
on or off,
not rear heater, been fooled on that one before too
when its in off, it is going low speed, turn it to speed 1 and its the same speed, all other speeds do increase.
also makes no difference if in defrost or heat floor mode, or any of them inbetween.
maybe it is a bad resistor, or bad switch....ill just let it go for now.But Im happy its working. up here this time of year its always on, this was prob first time since owning this rig ( month) that Ive probabally turned it to the off position and that was because I was playing with radio balance controls.

I do know this spring I need to pull the motor and clean the squirrel cage out ( noise esp on high) so Ill check the resistor then.

Luckily when I shut truck off, it shuts off so now power drain.


thanks

the last thing you could check up is the circuit breakers
if they are ok then it’s just some kind of safety measure or inner setting