mwk
Posts: 35
Joined: Wed Oct 25, 2017 8:15 pm
Location: Massachusetts, USA

"Auto" HVAC questions

Thu Feb 08, 2018 7:37 pm

So I've been driving my Bolt for a few months now and I have a question about the hvac. Specifically the "Auto" setting. I've read and re-read the owners manual but it just isn't really clear to me.

Is there a way to adjust what "Auto" means? In other words, in my car when it's set to "Auto", it seems to insist that the air in the car be recycled. As soon as I turn recycling off, the "Auto" light goes off too. The fan speed also seems to be fixed and if I touch that, the light also goes off. Another issue: I'm wondering about setting the temperature in the car. I hate an overheated car so I have the temp set to 63. But, I still find that it gets very warm and stuffy in the car. I haven't tried putting a separate thermometer in the car to measure it, but it seems absolutely certain that it's much hotter than 63 in the car once the heat gets going.

Is the temperature setting only effective when the car is in "Auto" mode? I'd turn off the heat entirely and rely on the heated seats, but I'm finding that the windows seem to start fogging up when I turn it off.

devbolt
Posts: 466
Joined: Wed Sep 28, 2016 2:17 am
Location: Bay Area, California.

Re: "Auto" HVAC questions

Thu Feb 08, 2018 9:38 pm

When you the car set to Auto, all you can do is select a temperature. The car then decides how to adjust the fan speed, heat/AC on or off, vent mode, and recirc mode, to achieve that desired temperature. Typically if you are trying to rapidly cool down the interior of a car, you want recirc on. If it’s cold out and you have fogging you want recirc off, but AC on (using the AC helps dehumidify the interior).

The temperature setting is active all the time. Set a fan speed of 4, set the vent mode to the dash mounted ones, and turn on the AC/heat and then slowly adjust the temp up,and down and there should be a change in the temp coming out of the vents. Try cranking it all the way to low for a bit, and then all the up to high and it should be readily obvious it is working with Auto off.

For me, I leave it in Auto most of the time, and adjust the temp up and down to get the desired air flow, which is usually a gentle breeze on my face. Occasionally if it is cold out, I raise the temp so the cabin gets warm, and then adjust the temp back down to a comfortable temp.

Some owners have reported having a problem with their Bolt blasting hot air when they had the temp set to 73 or 74, and the outside temp being above 80 or so. I believe it required multiple trips to the dealer to get it properly diagnosed and fixed. Something to do with a faulty sensor.

gpsman
Posts: 495
Joined: Thu Oct 20, 2016 9:10 pm

Re: "Auto" HVAC questions

Fri Feb 23, 2018 3:24 pm

I’ve been fairly disappointed with the HVAC system in this car. The Auto settings that is.

I find it works like the system in your house.
I get fully hot air, (or fully cold air) until the inside temperature sensor reaches its setpoint. Then the system cycles off.

Why can’t I get exactly 70 degree air coming out of the vents all the time!?!? This is a 2017 car!

It seems the “blending” does not work.
My older cars when you manually moved the blend door and could “set it and forget it” were nicer in my opinion.

I don’t care what the internal cabin sensor says. Maybe it is in the sun. Maybe it has been cold soaked.
Maybe it is being blocked by an object.
I care about the temperature coming out of the vent.
This “feature” seems to have been overlooked.

SeanNelson
Posts: 1367
Joined: Tue Jul 05, 2016 2:43 am
Location: Vancouver, BC

Re: "Auto" HVAC questions

Fri Feb 23, 2018 5:48 pm

gpsman wrote:Why can’t I get exactly 70 degree air coming out of the vents all the time!?!?

Well.... it's not quite that simple. If you set the temperature controls to 70 and the air coming out of the vents is 70 then you're going to be too cold if the Outside Air Temperature is around freezing on a cloudy day and you're going to be too hot if the sun is blasting in the windows on a really hot day. The system has to take those factors into account and deliver air that's hotter or colder than you've asked for to compensate.

That having been said, I agree that the system doesn't seem to compensate for these factors as well as the system in my Prius C did. In the Prius C I'd turn the dial up to "Hi" if I needed to get the car warmed up, but once it became comfortable I was able to leave it set at 23C all day long and it did a great job of keeping me happy. With the Bolt I find myself having to fiddle with the temperature knob, and it seems to have a pretty harsh transition from "slight warming" to "slight cooling".

EldRick
Posts: 363
Joined: Thu Dec 22, 2016 8:36 pm

Re: "Auto" HVAC questions

Fri Feb 23, 2018 5:53 pm

If you could set the airflow temp to 70 in winter, the temp in the rest of the car would be much colder, as it loses a LOT of heat thru conduction to the outside.
The difference from what you are used to is that the heat in an ICE car is wasted thermal energy from the engine, and there is lots of it, while in the Bolt, heating takes away range, so it needs to be much more efficient.

gpsman
Posts: 495
Joined: Thu Oct 20, 2016 9:10 pm

Re: "Auto" HVAC questions

Sat Feb 24, 2018 10:36 am

SeanNelson wrote:
gpsman wrote:Why can’t I get exactly 70 degree air coming out of the vents all the time!?!?


With the Bolt I find myself having to fiddle with the temperature knob, and it seems to have a pretty harsh transition from "slight warming" to "slight cooling".


I completely agree.
I also hate that the heat/air condition button is a soft key on a screen and not an actual button. Living in San Francisco Bay Area, most often I do not need either. But most often I need a little defogging the first 5 minutes of the day, and then nothing. So I find myself toggling this button all the time. And I hate that. I worry that leaving it it auto will waste energy running the AC compressor to dry the air, and then waste more energy from the resistive heater warming it back up. Double whammy.

gpsman
Posts: 495
Joined: Thu Oct 20, 2016 9:10 pm

Re: "Auto" HVAC questions

Sat Feb 24, 2018 10:45 am

EldRick wrote:If you could set the airflow temp to 70 in winter, the temp in the rest of the car would be much colder, as it loses a LOT of heat thru conduction to the outside.
The difference from what you are used to is that the heat in an ICE car is wasted thermal energy from the engine, and there is lots of it, while in the Bolt, heating takes away range, so it needs to be much more efficient.


I mostly disagree. My cold days are 45 and my hot days 85. I could live with 70 year-round. However I get your point that the cabin will warm faster on a 45 degree day if I temporarily set it to 80. I don’t care about the rest of the car. I’m solo 80% of the time and only the front seat is used the other 20% of the time.

My method of manual control is the most efficient. But it is annyoing. Auto is probably the least efficient. See my prior post.

provega350
Posts: 4
Joined: Mon Aug 13, 2018 1:00 am

Re: "Auto" HVAC questions

Wed Nov 21, 2018 1:33 am

I live in the San Francisco Bay Area. The temperatures here are moderate most of the time. I usually don't need heating or cooling. I turn the HVAC system on and off to regulate the temperature. I don't use auto because I feel it uses energy, running the AC, to cool the air, and then waste energy, using the heater, to warm it back up. All I usually need the system to do is allow fresh outside air into the cabin
to keep it fresh.

Is there a way to do this without having to run the fan? Is there a way to get outside air flowing through the Bolt without using the heater, air conditioner or fan? In the old days there was a duct, which ran from the front of the vehicle into the cabin, with a flap in it, which one could open or close.

trevmar
Posts: 12
Joined: Sat Jan 21, 2017 8:08 pm

Re: "Auto" HVAC questions

Tue Nov 27, 2018 12:07 am

Too bad there is no sunroof option - a tilted sunroof is a good way to extract warm and/or humid air from the cabin without using fans or a/c and only adds minimal drag.

Cars these days are becoming like houses - fully sealed and then needing "air management"

PackardV8
Posts: 79
Joined: Mon Jun 12, 2017 2:39 pm

Re: "Auto" HVAC questions

Sat Dec 01, 2018 9:02 pm

trevmar wrote:Too bad there is no sunroof option - a tilted sunroof is a good way to extract warm and/or humid air from the cabin without using fans or a/c and only adds minimal drag. Cars these days are becoming like houses - fully sealed and then needing "air management"


JMHO, but I love that the Bolt does not have a sunroof. I detest those expensive, failure-prone, rattling, leaking, headroom-stealing abortions. Your opinions and results may differ.

jack vines
My vehicles
2017 Bolt Premier Cajun Red
2011 Saab 9-4X
2005 Saab 9-5
1998 Saab 9000 Aero
2004 Ford F250 6.0 Turbo Diesel
1963 Studebaker Avanti
1956 Studebaker Hawk custom with a supercharged Packard V8
1955 Studebaker custom pickup with a Packard V8

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