In my 97' 4Runner the heater has not been working for some time (blows cold air). Both hoses going thru the firewall get hot when the heater knob is on heat. Water valve works fine, A/C also works fine and there's no problem with the thermostat.

Yesterday I was checking under the dash (passenger side) and by chance I found this white plastic mechanism (blend door?) with a little knob. I moved the knob to the other position, heard some vent doors opening, and Voila, like magic, hot air started flowing thru vents. My questions:

1) What is the function of this mechanism? especially since the regular heater control knob on the dashboard can now successfully control the hot/cold air thru the vents.

2) What controls this mechanism (surely one isn't expected to go under the dash to manually move it).

3) Is it ok keep it in this new position, or would I get into other problems.

Appreciate any help!

 

I was searching the site for Heater problems as I am currently experiencing COLD air syndrome! So I stumbled across this one, with absolutely no replies I might add. And guess what....it helped me fix the problem. I went under the passenger side dash and found that white control arm and messed around with it. Well it moved and low and behold WARM air began to flow. It was like Xmas all over again!!!!
I have been freezing my arse off for over 2 weeks now and when I was putting it on re-circulate, to at least get some warm air. Well, I couldn't see out my windows because of all the interior ice and fog!!

So, I figured out that the white control arm is actually for the warm/cold selector. I am guessing that the cable is either broke or disconnected somewhere, somehow. Not sure why, considering I don't ever move this, that I can think of. So I will check later tonight as to where it has come apart but just so glad I have HEAT now!!!

 

It's called a blend door. As you increase the heat lever, the door should expose more of the heater core. When you decrease the heat lever it should block off the heater core.
There must be a cable missing or disconnected somewhere.

 

This sounds like almost exactly what was happening in mine too in this thread:
https://www.yotatech.com/forums/show...785#post513785

Can you guys take a pic and post it for what you had to mess with?
I will be taking it apart next weekend so I will post too when I get a permanent fix.

 

Eventually I will get a digital camera and be able to post some Pics.

The white lever is very easy to spot its almost directly behind the center console near the passenger side. I can lean over from the driver's side and put my hand underneath to move the arm.

I hope this works for you....as I suspect it will. Otherwise just change your thermostat.

 

I had this problem too. cable got kicked off by someone in the footwell of passenger side. cliped cable back on and heat works again... love yotatech.

 

The appears to be the exact problem that I have. Where exactly is this control arm on the passenger side? Close to the center console?

 

same thing happened to me! two weeks with cold air and couldn't figure out why...flicked the lever and finally hot air! thanks yotatech and the search function!