[klausc]

It has been a bit chilly around here lately. My daughter's climate control works, somewhat. The system only does floor heat in the auto mode, regardless of cabin temperature setting. Needless to say, her right foot is burning and her hands have icicles.

I can set the mode to bi-level, but then the fan speed increases, even after the cabin is toasty. So then I need to reduce the fan speed... Why bother having "Auto"????

Is this 'normal' for Subaru? I am used to European cars where the climate control temperature is set once, and never touched again - the vents automatically open/close and blower reduces/increases speed depending on desired temperature.

 

[rasterman]

Not normal. Something has gone wrong in that car.

There is a built-in diagnostic program for the HVAC controller. I don't know the secret handshake to activate it but it is on this board somewhere.

Probably just a stuck air vane; the servo can no longer move it to the correct position to change delivery target. Not a fun repair.

 

[klausc]

I don't believe anything is physically stuck or broken. Pushing MODE instantly opens/closes the corresponding vents. AUTO seems to invoke floor only. And I did warm the car up nicely during the test run.

 

[rasterman]

Fair enough.

I don't think I ever consciously noticed whether "AUTO" indicates on the display whether it is sending the air to floor, dash or both. I can confirm that I do get warm air from both footwell and dash vent when I leave it set to auto and drive in cold weather. I don't get a lot of air volume out the dash vents when set like that, but overall heat delivery has always seemed appropriate.

Your description of control usage in your Euro car also describes my experience with my 2006 Outback.

 

[Logie_OBXT]

It's not that it's stuck, it's that the servos forget how to behave. They constantly hunt for their position and sometimes seize at the end of their control movement.

If you turn the car off, do you hear kind of a gentle griding or grunting sound? Or maybe it sounds like running water coming from behind the dash?

I have video somewhere that I took of my actuators constantly hunting for their position, but can't find it at the moment. On mine, if I try to have heat on my feet only, it hunts between defrost and my face and feet, but if I set it to defrost only, it's fine. For A/C, it's fine as long as it's at my face only. If I try to do face and feet, it goes all over.

 

[klausc]

The vent motors are quiet. When I push on the MODE button and change the setting, it is almost instant change. No noise after shutdown. I wonder if it is the cabin temp sensor that is taking so long to warm up?

If there is an error in the unit, can I reset the codes by pulling the fuse with the ignition switch in the on position?

 

[dyqik]

One thing I find on our Prius in the extreme cold when it's set to auto - the temperature sensor doesn't seem to notice that it's cold in the cabin and start the fans to distribute heat until the fans are manually turned on to move some of the frigid air past the temperature sensor. Either that, or the control algorithm is confused by the very low temperature and gets stuck in some kind of "out of range" state. Something similar may happen when there's a big differential between the cabin temperature and set point.

One thing about the bi-level mode: The fan speed will probably stay high in bi-level mode until the air is close the set point. "Toasty" while you are bundled up could be as low as 60F or so, and a set point in the 70s will feel ridiculously warm. There's a tendency for people to turn the thermostat up when the temperature is still way below the set point, in the mistaken belief that it will warm things up faster (I regularly have to explain this to physicists...). (could be teaching my grandmother to suck eggs here, sorry if I am...)

 

[klausc]

I have also admonished quite a few folks who insist on moving the temp hotter or colder to 'speed up' the system. Leave it alone!

Initially, I guessed HAL had screwed up because the car was parked outside overnight and the temp was -18F when the car started up. But since then, the car was garage parked with the temp at start up around 28F and the outside air at around +10F. In the latter environment, I drove some errands and after 30 minutes, the air was still blowing at the feet and very hot. I changed the MODE to bi-level, still high speed, and then slowly turned the temp from 69F down to 65F, when the A/C turned on!! If not the A/C, then it might have been just cold air from outside. At the 69F setting (both sides), the blower speed eventually started to decrease while in the bi-level state.

The air is always drawn from outside, the recirc button is off.

 

[Zedhead]

FWIW, I never use auto in the winter. I can always make better decisions on what is needed faster, and with better results than the (so called) AUTO function.

Living in Northern Mn. Most of the time it's just set to 85 and occasionally set to different outputs/fan speed.

 

[jonnylaw13]

when its cold out my auto starts on defrost for a few mins but then switches to feet and stays there, which for me is my preferred setting, unfortunately my feet setting is absolutely terrible, once in a blue moon it will adjust the fan speed but by that time ive got the windows open because im sweating me arse off

 

[rasterman]

I have also admonished quite a few folks who insist on moving the temp hotter or colder to 'speed up' the system. Leave it alone!

Initially, I guessed HAL had screwed up because the car was parked outside overnight and the temp was -18F when the car started up. But since then, the car was garage parked with the temp at start up around 28F and the outside air at around +10F. In the latter environment, I drove some errands and after 30 minutes, the air was still blowing at the feet and very hot. I changed the MODE to bi-level, still high speed, and then slowly turned the temp from 69F down to 65F, when the A/C turned on!! If not the A/C, then it might have been just cold air from outside. At the 69F setting (both sides), the blower speed eventually started to decrease while in the bi-level state.

The air is always drawn from outside, the recirc button is off.

There is a poorly handled feature in the automatic HVAC system of that era. The lowest and highest setpoints work like overrides, but there's nothing to indicate this on the display. It just says 65 when it hits low override, and 85 (I think?) for high. In later model years they revised it- they kept the same behavior but the display actually says "Lo" and "HI" instead of numbers once you hit the end of range.

 

[jon_slider]

I just went out and started my car, turned off the HVAC, and then turned it back ON (to Auto Climate).

this was the initial display, airflow from the dash vents:

within less than 1 minute the display changed to this, airflow from dash vents plus floor:

iow, the mode changed from dash to dash plus floor, Automatically

ymmv based on outside and interior temperature. atm here outside is 62F, and the car was driven less than 1 hour ago. I would not be surprised if I was in freezing temperatures, and the car has cold from sitting overnight, if the Auto Climate decided to give me floor heat only.

a couple things Ive learned
IF I turn off climate control, the HVAC remembers, and continues to use the last mode setting before turning off. It also remembers the last temperature setting, and continues to deliver that level of heat. What turns off when I turn off climate control is the AC and the fan.

Now a special note about the 65F setting, with Auto Climate ON, that actually means Heat OFF, and IF I do not turn off the AC by hand, it WILL come on, IF the cabin is warmer than 65F

bottom line, I can use Auto, and I can also modify the mode, turn off AC, and modify the fan speed, while Auto Climate display is still ON. This means my custom manual settings will remain in effect as long as I do not turn off climate control.

If I turn OFF climate control, the last set Temperature and Mode will continue to operate, just no AC, and no Fan.

IF the goal is to have dash and floor heat, at the fan speed of your choosing, just manually set it the way you want it, and it will stay that way, until you turn OFF climate control. The next time you turn it ON, it will operate the AC and fan speed and mode, that the system wants to use. And it will change as the cabin temperature changes.

 

[klausc]

Thanks Jon, That is the way this system used to work.
I wonder if the passenger side airbag replacement screwed it up. It is too darn cold to play around with removing the panel and checking the air tube from the cabin temp sensor. Why is there even an 'air tube' needed for the temp sensor? A small fan at the sensor is all that is needed, no need to route the air some place else.

 

[jon_slider]

The climate control can be quite puzzling..

I did some testing and figured out how to make the heater blow on my feet the whole time, without sending heat to the center console.

The trick is to set the auto temperature too high.
If you look at these pictures you can see that my Subaru has decided that at 74 I need the heat on my feet:

At 72 it decides to use both feet and center console:

And at 70 it sends to center console, not feet.

Interpretation:
When the car has decided it needs to raise the temperature of the cabin, it sends all the heat to the floor.

If the car decides it needs to lower the heat in the cabin it sends the air to the center console.

Note
The dash vent near the doors is independent of the center console, and flows heat all the time. Both when heat is coming out the floor vents, and, it also comes out of that side vent when output switches to center console.

If your daughter wants to warm her hands while the heat is coming out of the floor vents, she just has to put her hands to the left of the steering wheel.

And if she does not want the heat to come out of the floor continuously, then she should not set the climate temperature target too high.

 

[klausc]

resolved

Cabin temperature is set to 69F. With the January thaw, low 40F's, my daughter reported this morning that the climate control went to the center vents automatically!!!

I guess the Japanese don't know how to control temps when the outside temps are way below 0F. Getting hot feet while freezing to death is probably not known in a marine climate.

Today, I tried it with the garage at close to 50F. The feet came on first, as expected, then the defrost(?) followed by bi-level. What a system!

 

[jon_slider]

glad you figured out that the system works to change from feet, to defrost, to center, all automatically

hot feet while freezing

I like using the electric heated seats when first getting into a cold car, and the climate control has not yet brought the cabin up to comfortable levels.

Does your daughter not use the seat heaters?

 

[klausc]

You don't know what cold is until you sit on leather seats that are -20F. Of course the seat heaters are ON, usually for the entire trip!

 

[jon_slider]

You don't know what cold is until you sit on leather seats that are -20F. Of course the seat heaters are ON, usually for the entire trip!

true, I have no idea what its like to drive in that temperature.

Sounds like the cabin never gets warmed up.. Which makes me wonder, is the drive relatively short?

not to be disrespectful, you clearly have experience I lack.. just curious

 

[DavidPeab]

I usually end up just overriding the automatic climate control in our 2008 LL Bean until the car is warmed up. It typically ends up blasting the fan on the highest setting to try and heat up or cool down the car ASAP. I'd rather hear the radio and wait about ten minutes of manual adjustments before letting auto take control.

The auto in my Honda works a lot more intuitively and smoothly, but that car is 10 years newer and has the benefit of newer technology.

 

[klausc]

I suspect that the cabin temp sensor is in a poor location, plus the incoming air is below zero so the 'mix' is thrown off.

My daughter's commute is 45-60 minutes, one way, plenty of time for the engine to get nice and warm. The temperature gauge is in the middle of the dial where it should be.

The seat heaters are not up to par compared to my 1998 Volvo seats. On the Volvo, the entire surface is heated. The Subaru only has the center panels heated, so the 'leather' touching your thighs never gets warm; kind of like the 1975 Volvo.