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What's the point of motorized manual HVAC control?

Posted: Mon Aug 13, 2012 3:41 am
by 91Beater
Perhaps the ducting and actuators are shared with the full fledged automatic system and Subaru wanted to avoid having to use different parts.

The HVAC control on our Legacy is one of the dumbest design ever. The 95 andup are slightly better but still motorized.

Biggest issue is that you can't put it into recirculation mode without turning on the A/C compressor. It's a feature that's used fairly often to avoid noxious smell from coming in.

There doesn't seem to be an ability to hold the air path to last used. When you turn it off, something moves. When you turn it back on , it moves back. That's unnecessary wear on actuator and something to go wrong.


Vent = straight at you.
BILEV = bottom and front
HEAT = bottom
DEF/HEAT = bottom and windshield
DEF = windshield

I didn't know how it worked until I looked in Haynes. I don't know why they didn't just use common pictograms.

/rant

I'm frustrated that I had to repair the circuit board on switch box for something so simple. I don't know why they couldn't have just used all mechanic setup that is much more flexible.

Re: What's the point of motorized manual HVAC control?

Posted: Mon Aug 13, 2012 4:35 am
by Alphius
Euro Legacys had a better control I think. More like the second gen ones. I have often thought about trying to get one and seeing if I can retrofit it into my car, because the recirc/AC controls bug me. I like running A/C split between vents and feet and you can't do that with ours, but you can with the second gen controller.

On the other hand, I have no problem with a motorized one. In fact, I prefer it. They reduce effort and provide more blend choices at the push of a button. And at least with a well designed system (like ours) they rarely ever break.

Here's a Euro controller:
Image

And a second-gen one:
Image

Re: What's the point of motorized manual HVAC control?

Posted: Mon Aug 13, 2012 6:26 am
by 91Beater
This is the best setup in my opinion for manual AC
http://www.quierouncarro.com/vehiculos/ ... 1990-2.jpg

All manual fresh/recirc and even in between damper lets you open/close the ram air that comes in. It's great for keeping constant hot air going to windshield in the winter without having to turn on the fan.

All manual is win. You don't need to use AC to defrost. You only need it to defog.

Re: What's the point of motorized manual HVAC control?

Posted: Mon Aug 13, 2012 4:42 pm
by evolutionmovement
It's because of the effort to pull the cable, the design of the HVAC controls is more limited in termes of looks and ergonomics, it's a matter of following the industry to look current (manual controls would have been criticized for seeming outdated vs. the competition and Subaru was trying to move upscale, not seem bargain basement), also routing a manual cable system under a crowded dash is probably difficult. My Mazda3 couldn't recirc without the A/C either. The Focus can, but you have to put it on A/C first and then turn back the cold selection dial one click (the final click puts you in recirc-A/C) and manually turn off the A/C. I think it's more tricking the system than by design allowance. Recirc can't be used with the defrost. IIRC, our E150 vans didn't do it independently, either. I never bothered to notice on other cars. A/C often helps defrost considerably by drying the air, not just blowing on it, highly humid air often being the problem it's there to resolve. Newer vehicles have A/C compressors that have almost a negligible effect on mileage (though it still kills the already gutless off the line takeoff in the Focus).

Re: What's the point of motorized manual HVAC control?

Posted: Mon Aug 13, 2012 5:21 pm
by DD50
I would like a separate recirculate button but the controls aren't too bad. Really my biggest problem is how noisy the system is when I switch vents. lol funny to listen to but sometimes annoying especially when I'm asked why it does that

Re: What's the point of motorized manual HVAC control?

Posted: Mon Aug 13, 2012 5:47 pm
by subaru_styles
Ive always wondered if the euro heater controls would work in our cars

Re: What's the point of motorized manual HVAC control?

Posted: Mon Aug 13, 2012 5:56 pm
by kimokalihi
The base model legacys with manual windows and no ac have a recirc button. I saw one in the junkyard.

Re: What's the point of motorized manual HVAC control?

Posted: Tue Aug 14, 2012 1:04 am
by Alphius
kimokalihi wrote:The base model legacys with manual windows and no ac have a recirc button. I saw one in the junkyard.
This is also true.

Re: What's the point of motorized manual HVAC control?

Posted: Tue Aug 14, 2012 1:05 am
by Alphius
subaru_styles wrote:Ive always wondered if the euro heater controls would work in our cars
You should try it and let me know. ;)

Re: What's the point of motorized manual HVAC control?

Posted: Tue Aug 14, 2012 1:05 am
by evolutionmovement
But no A/C, probably. My no A/C cars had recirc, too. I'm not really sure why it's so common to run the A/C with it if the car is so equipped, though.

I actually like the sound of the HVAC. It sounds like a machine doing work, which is what it is. But I know I'm weird, I also like the notchy shifter (I wouldn't want every car to be notchy, but I think it fits the character). Refinement is good, but it gets boring.

Re: What's the point of motorized manual HVAC control?

Posted: Fri Aug 17, 2012 6:09 pm
by Legacy777
Just to add to the comments....I don't notice mine being overly noisey when changing positions. The grease may be dried up, which might be why it's noisy.

Besides the going "upscale" that Steve mentioned one of the main reasons they made it so you can't do recirc without AC is because of windows fogging up. The 90's were a time of passive safety BS, like the seatbelts, which eventually gave way to common sense. So even on most new cars, you can put the HVAC system into recirc without the AC on. However I have noticed that most electronic systems will usually default back to fresh air after a while.