heater control box issue

[b_hickman11]

Originally Posted by DevilGirl

It actually is a setting. At least on mine. There's a dot there. And it "clicks" into place there too. There's just no picture there, other than a dot, to indicate the actual halfway mark between the 2.

If you turn the knobs while the car is turned off and listen to the flappers opening and closing you will not hear a big change from the picture settings and the dots in between. But when you move it from the in between dot to a picture, you will hear the flapper open or close all the way(depending which what you are turning the knob). Therefore, when you are one of the dots, the flap is barely open or barely closed. So if you turn it from the upper vent setting to the mid dot between vent/floor setting, this will cause the lower flap to barely open up, causing less air flow to reach the floor.

[DevilGirl]

Originally Posted by b_hickman11

If you turn the knobs while the car is turned off and listen to the flappers opening and closing you will not hear a big change from the picture settings and the dots in between. But when you move it from the in between dot to a picture, you will hear the flapper open or close all the way(depending which what you are turning the knob). Therefore, when you are one of the dots, the flap is barely open or barely closed. So if you turn it from the upper vent setting to the mid dot between vent/floor setting, this will cause the lower flap to barely open up, causing less air flow to reach the floor.

Let me explain. Prior to the holiday, that was the only setting I had used and it was perfectly fine. The car sat, in a garage, from Thursday afternoon till Monday morning. It was not until Monday morning that I had any issue at all. The settings were not changed from Thursday till Monday.

Your theory does not apply. It would apply if something were changed between the time it was parked (when it worked properly) to the time it was used again (when it didn't work properly), but that is not the case.

[CTScott]

I just checked the effect of the knob on Crashy, who's air box is fully exposed, so I can see what happens when I adjust the air flow direction. There is a definite difference between Feet, Dot, and Defroster+Feet as far as the mode control dampers go. There are two sets of dampers (plastic flaps) that move when you turn that knob - An upper set of three that control flow to the defroster and/or center and side registers and a lower set that controls flow to the front and rear foot wells. The chart at the bottom shows the differences in flow for each of the settings. In the Dot mode, watching the dampers move, I'd say that the intended flow in that mode is equal output from foot and defroster.

I think what probably happened is that the lower one was sticking in the closed position and the cold air you were feeling down at the feet was probably just leakage through the firewall.


Heat - Chart.jpg

[b_hickman11]

Originally Posted by DevilGirl

Let me explain. Prior to the holiday, that was the only setting I had used and it was perfectly fine. The car sat, in a garage, from Thursday afternoon till Monday morning. It was not until Monday morning that I had any issue at all. The settings were not changed from Thursday till Monday.

Your theory does not apply. It would apply if something were changed between the time it was parked (when it worked properly) to the time it was used again (when it didn't work properly), but that is not the case.

Does the Yaris have more than 1 heater core? What was the outside temp on the days it was working compared to the days when it was not working? Are you using fresh air or recirculate?

ps...maybe a raccoon crawled up in their to get out of the weather and stopped up the vent.