I'm experiencing a heating issue (problem) on my wife's 2001 4Runner Limited.
The problem is that when heater is on and it blows hot air from floor ducts it does blow cold outside air from front passenger foot duct. This means that the truck can be worm and nice and passenger at the same time feeling like he has his leg in ice cube. If I put recycle air switch on to use only inside air, it start working normal, but from my understanding because it takes warm inside air. Driving all the time with recycled air on is impossible as windows get foged within a minute to can't see through stage (outside is -25 degrees).
Note that I have Auto Climate Control.
My understanding of the problem is that this particular duct (front passenger foot area) somehow doesn't get air through the heater using instead unheated air from the source. This is why it icy cold when recycle air is off and system takes outside cold air.
I tried to find a solution, but my Haynes Repair Manual doesn't give a solution and I can't find it anywhere in the web. Driving to the dealer will get me down on cash as they charge $125 for diagnostic + repair ($105 per hour) and 13% tax on top of that all. It can be ~$500 repair if not more there and I'm not sure if any parts need to be changed.

NEED YOUR HELP.
Can anyone suggest or help with anything regarding my issue. At least figure what is wrong and how to fix it. I have a mechanic who can do the work in the garage (its just too cold for work on the driveway), but he needs parts and knowing what need to be fixed for making it less in cash.

 

Any ideas?....

 

I'm having trouble find what is wrong. Haynes manual doesn't help at all.

 

All that i can think of is to trace the duct and see if there is a flap of something stuck the wrong direction along the track

 

That's good idea.
I did also found a draft this afternoon, but can't locate the place it goes from. It somewhere around the blower motor.

BTW, I thought may be cabin filter got clogged, but can't locate its location. Anyone knows where is it?

 

As far as a draft i have no idea but i do know that the 3rd gen doesn't have a cabin filter.

 

I don't have the Auto A/C but I have a world of HVAC troubleshooting experience on a 1985 BMW 735i that was in the family for almost 20 years. HVAC was the most trouble-prone thing on that car.

That kind of problem is--duh--some actuator not working as it should because it is broken or it is getting the wrong signal. I pulled my FSM looking for a diagram of the ducts/register structure. Did you know those a/c units can do their own diagnostic check on position sensors (yes, it has those), actuators, and everything else. It then throws the trouble codes up on the readout. ($125 to push two buttons and turn a key--gotta love the stealers!)

To go into DTC mode: Hold the Auto and R/F switches down. THEN turn on ignition key. It will do indicator check and then run its diag routine. Too cool! Code goes up on temp panel. Hit OFF to get out.

To understand the codes get an FSM or look online. Or post back and I'll look it up for you.

My guess is your problem is AIR/MIX actuator right behind glove box is not achieving correct register and shorting cold air straight into the foot duct. The WHY is a far more complex question. The FSM shows how to test it and the associated position sensor. But the diagnostic routine comes first.

100 Posts! Yay, me!

 

Will do. What R/F is stands for?

 

I think "R/F" means the Recirculate/Fresh air button.



FOG

 

I see. In my case its 2 buttons - one for outside air and another for inside air which are switching between each other when pressed.

 

My FSM is '99. I'm sure your year has something similar. ncttora has the 2002 FSM online. I'd look over there to see if there is a different routine for calling the diagnostic mode in later models. The AC chapter is near the end.

Edit: I was curious so I looked. The instructions are the same as I have. It is actually in the Diagnostics volume, not the AC chapter itself. Here is the

Linky

There is a drawing of the panel so you can compare it to yours.

 

Looks like the same panel. I'll see it tonight.

 

It gives me code 21 and flashing "Face" direction of airflow as well as "Empty" fan bars.
What can it be?

I've done the test 5 minutes ago and it was dark to see anything else. PDF says it may display 21 if its dark outside. Should I do it daytime tomorrow?

 

Are you sure 21 was the only number? It displays a code for 1 second and stops on the highest. Your problem is not the solar sensor (DTC 21), there is just no sun. I would repeat the test using DEF to step through the actuator/sensor tests to be sure there are no codes.

Do you get cold air through that floor duct when it is on the top vent setting--or is it off? Because there are two servo actuators, AIR/MIX and AIR/OUTLET. I suspect one of those, but no idea which I would pull out first. My diagram is just not very good to try to imagine flap positions that would cause this. I'll look at my rig tomorrow and post back. Or maybe somebody else has a better idea. In the meantime, a rag in the foot exhaust might be better than a cold blast. It would also be interesting to see where that cold air would go then.

Here is another thought: what if the silly A/C is not turning off when not in defrost mode? Thus cooling off your nice warm air. A quick eyeball check on the compressor clutch would rule that out. My BMW did the opposite for a time, kept the heater on in A/C mode.

 

Looks like it was the only code. The check was done quickly and tried to go steps, but nothing come on. After a few seconds the only number apeared on display was 21 and it was flashing all the time. I went ahead and done the second part of the check (per instructions), but its difficult to say as it shows some closed and open positions which are not visible, but I did feel the air in right places and heard sound of valves opening closing.
The cold air blowes from the duct when it selected FLOOR, so it does blows when suppose to, but only cold outside air. Think of getting negative temperature outside air in your feet when you set your unit to 72 degrees and it feels 72 by everybody else in the cockpit, while your feet are below 0. . A/C is looks like off, but why it would be on and work for one vent only?
So issue is still open and so far I can't find what is wrong...

 

I looked at my rig today and that 'one vent only' thing is very strange indeed. Both passenger footwell and driver's footwell outlets are fed by the same duct. I can pass a vinyl hose from one side to the other. Are you really getting heat on the driver's side and cold on the other? I strongly suggest you try my idea to stuff a rag in the outlet on each footwell in turn and see what comes out the other. Are you sure that that cold air is from the footwell duct and not a draft from somewhere else? Is the cold air related to vehicle speed or is blower speed?

Until this is understood, further trouble shooting is impossible, IMHO. [Perhaps we have a case where your perception and your passenger's are different. My GF will complain she is not getting heat until things are at the point where plastics melt.---j/k] Good luck.

 

Very interesting about driver and passenger duct. I'll look if I have the same. Are you saying that you can pass the hos or wire from one to another?
It blows from the blower as truck is still. When it moves it doubles with airflow from speed.
As perception. I tried sitting in both places and we changed with my wife places with same results. When I tested it a few days ago, I tried my hand and it was blowing cold from passenger duct and hot from driver; one hand, so same perception. I do have a small draft somewhere from under the dash where blow motor sits (strange, but I can't find where it coming from as no visible cracks or holes). This draft only makes thing worse, but mainly it is duct which blows cold air. I asked dealer and they do not know and want truck for inspection. Will see, if I wouldn't be able to find the answer, I'd be force to drive to the dealer.

 

Mine may be different, due to manual control. If it is as you say, I guess there is no other way to proceed except to open her up. I can't figure how EITHER actuator could cause this. (And, how can ONE blower supply two different temps?) I wish I had a better diagram to figure out the flows in each mode. Sorry I can't be more help.

 

The same is with me... I can't understand unless system somehow bypass the heater for this particular duct.