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Discussion Starter #1
I'm putting a call out to Vancouver area 2017 - 2018 Bolt owners; I'd like to see how the climate control system in your car works when you adjust the temperature. I often find that in the shoulder seasons it will either be too cold or too warm in the cabin, despite the same temperature being called for. Adjusting the temp up a degree will cause it to get way warm, dropping a degree will cause immediate cold air to blow (all heat stopped) and air conditioning starting up. It wildly over compensates for the small change.

I've had it into GM service while it was under warranty, but they told me it was behaving as intended. Now that it's out of warranty and it's my problem, I'd like to confirm the behavior is not normal, and if so dig into it and correct it myself.

Thanks in advance
 

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My 2019 does the same thing when set to "auto". My guess is the software compares outside temp to cabin temp and to the setting and turns on heat or A/C to keep you comfortable. Or at least what the software thinks your comfort level is. It really bugs me that the heat comes on when I want the A/C on.
 

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I'm here in the Vancouver BC area, but I'm going to be out of town until next week.

Yes, the climate system has this annoying crossover point between "heat" and "cool" modes - it's not just your car and so it seems to be "normal". I preferred my Prius C which allowed you to adjust the temperature in 1/2 degree Celsius increments.
 

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I preferred my Prius C which allowed you to adjust the temperature in 1/2 degree Celsius increments.
So I assume your Canadian model Bolt will adjust in 1 degree C increments? In the US we can adjust in 1 degree F increments, which is approx 0.5 C increments over a "comfort" range of 20-25C or so.
 

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So I assume your Canadian model Bolt will adjust in 1 degree C increments? In the US we can adjust in 1 degree F increments, which is approx 0.5 C increments over a "comfort" range of 20-25C or so.
Your assumption is correct. Unfortunately you can't switch the temperature adjustment to use degree Fahrenheit unit without also switching the odometer and speed displays to miles, which is IMHO impractical up here in Canada.
 

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My 2019 is touchy like that too. I think it's because the temperature sensor is in the plastic cover in front of the rearview mirror. I keep mine set on 73F as that seems to give me a decent balance between sunny and cloudy days/night driving, but sometimes the AC will overcool on hot days when it is sunny. The other day, it kept the fan speeds on a high setting long after the cabin had cooled down. It was a lot cooler in the cabin than normal yet the AC was still blowing fiercely. I reached up and touched that black cover behind the rearview mirror and it was HOT to the touch (presumably due to the sun beating down on it) even though the cabin was too cool.

Mike
 

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...sometimes the AC will overcool on hot days when it is sunny. The other day, it kept the fan speeds on a high setting long after the cabin had cooled down.
I've learned to just hit the fan "up" or "down" buttons to raise or lower the fan speed. There doesn't seem to be any way to get fully "Auto" mode to do exactly what I want, so I hit "Auto" and then adjust the fan speed to suit my taste.
 

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Discussion Starter #10
@MikeyBolt I've been doing some homework on the climate control system in the Bolt. It takes input from the window temp sensor (behind the rearview mirror), sunload from the ambient light sensor in the dash, external temp sensor (think it's at the front of the car), and two temp sensors in the ducting under the dash. I pulled this info from the GM service manual when I started getting serious about this issue.

I originally thought I might have a problem with a temp sensor in the duct measuring air in the cabin, perhaps a pinched wire as per the early recall, but the post by The Other Tom got me thinking; I wonder if the people at GM mucked up a temp conversion somewhere in the algorithm for calculating heating or cooling load. If a sensor(s) input is skewed by a bad conversion from F to C (GM is a US car brand, built for the US market first), it could cause runaway conditions and be overly sensitive to temp dial adjustments. So for fun I flipped my units over to imperial and have been running that for the past week and a half.

In that time I've been bouncing around between 72 and 74 degF on the temp selector dial, but it's been a huge improvement. While the temp I ask for isn't always comfortable, what really makes the difference is being able to ask for a degree or two either way and not have it either run 100% hot or cold in a wild over-reaction. It will warm exactly like the other EV's I've driven recently, and while the cooling after asking for a lower temp might be a touch more aggressive than I'd ask for, it does settle in at the lower temp as expected and I can be comfortable.

For me it's always the shoulder seasons that cause problems, when the car doesn't know if it should be heating or cooling and adjustements of 1 degC create huge over compensations. It's really tough to get a steady, comfortable temperature in spring and fall. Without doing back to back testing in a controlled environment it's tough to say with 100% certainty, but having lived with this issue for 2-1/2 years after GM techs tell me the car is fine because it heats and cools, I have definitely noticed a change in behavior after flipping over to imperial units. I've lived with the car long enough to estimate my driving range by looking at the scale and ignoring the numbered estimate, and I have navigation apps to tell me actual speed (if I care), so I'm going to continue driving this way for a while and decide what my next step will be. I may flip back and forth a couple times to try to improve my certainty in the cause of the issue. If it's indeed a programming bug I'll have to go back to GM and specifically pay them to check for an update to the HVAC control module. Now that it's out of warranty I should be able to pay them to do a specific task, whereas before under warranty they would be following the service manual troubleshooting guide which would conclude that the system is working because it heats and cools.

Will update when I have anything meaningfull to add. Sean Nelson, if you decide to run this test as well let me know how what your result is.
 
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