HVAC me please

  • Thread starter Thread starter Brawndo
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Godfrey said:
I've wondered about this as well. When I'm heating the cabin, what does the AC button do? Is it a way to activate/deactivate the heat pump? Or is the heat pump being used either way and the AC button helps dehumidify or something?
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The AC button should activate "air conditioning" mode from the chiller, effectively running the loop in reverse. As for the mythical "heat pump" dehumification, that does not exist because the water condensate is a self-contained closed system.

Household heat pumps systems generally have interior and exterior condensate drain lines but it would be bad news bears frozen-line-no-heat for EVs.
 
teslarati97 said:
The AC button should activate "air conditioning" mode from the chiller, effectively running the loop in reverse. As for the mythical "heat pump" dehumification, that does not exist because the water condensate is a self-contained closed system.

Household heat pumps systems generally have interior and exterior condensate drain lines but it would be bad news bears frozen-line-no-heat for EVs.
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Now it's cold, mine will heat with 'AC' on. It also defaults to 'AC'. I'd love to know what it is actually doing.
Last week was around freezing. I've taken a ~25% range hit. Maybe I'll try no heat and a warm coat tomorrow afternoon.
 
pictsidhe said:
Now it's cold, mine will heat with 'AC' on. It also defaults to 'AC'. I'd love to know what it is actually doing.
Last week was around freezing. I've taken a ~25% range hit. Maybe I'll try no heat and a warm coat tomorrow afternoon.
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See @Puppethead's Green+ mode experience in Minnesota at -3 ºF. He even rolled his windows down to avoid fogging the windows!
 
In my experience having the “AC” on in cold weather with the temperature set to “normal” results in the system removing the moisture from the air which helps stop fogging.
If you turn off the AC but set the windshield defrost to on most cars turn the AC back on.
 
pictsidhe said:
Now it's cold, mine will heat with 'AC' on. It also defaults to 'AC'. I'd love to know what it is actually doing.
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Basically, it's cooling and heating at the same time with only the one compressor (EKK) by using valves.

The HVAC fan is blowing through the cold evaporator (10) then blowing through the hot heat exchanger (11) then into the cabin. The air blowing over the cold evaporator chills the air and reduces the humidity, then it heats it back up by blowing over the hot heat exchanger

"If the heat pump is used in the mixed operation, the shutoff valves with the numbers 17, 20 and 21 are open. The shutoff valve with the number 18 is closed as there should be no reverse flow. This results in a division of the hot, high-pressure refrigerant. On the one hand, cooling of the high-voltage battery unit and dehumidification of the passenger compartment can be realized by the cooling at the evaporator, on the other hand, the divided heat transported with the refrigerant is used for the heat pump heat exchanger."

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SmartSelect_20221122_093051_Adobe Acrobat.webp
 
While that is the BMW i3 heating/cooling circuit, it should be slightly different for the MINI as the coolants to my knowledge are R1234YF for the A/C (plus heat) and water/glycol for the HV battery. Probably just physical space limitations with a retrofit?

It's certainly more elegant for the i3 using a dead simple HV battery cooling line compared to the MINI's individual module/pack hose connections.

i3cooler.webp
 
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teslarati97 said:
While that is the BMW i3 heating/cooling circuit, it should be slightly different for the MINI as the coolants to my knowledge are R1234YF for the A/C (plus heat) and water/glycol for the HV battery. Probably just physical space limitations with a retrofit?

It's a certainly more elegant for the i3 having a dead simple HV battery cooling line compared to the MINI's individual module/pack hose connections.

View attachment 19009
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True, I hadn't noticed that difference. Fundamental operation should be the same though.

I'd imagine that MINI is just using another heat exchanger between the refrigerant loop and the battery loop (attached at 7) because otherwise cabin temp set point would be tied to the battery temp control and that would be bad
 
Carsten Haase said:
True, I hadn't noticed that difference. Fundamental operation should be the same though.

I'd imagine that MINI is just using another heat exchanger between the refrigerant loop and the battery loop (attached at 7) because otherwise cabin temp set point would be tied to the battery temp control and that would be bad
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There should be a chiller and heat exchanger that's sort of in the "Yellow S" part of the MINI.
MINIchiller.webp
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insightman said:
If one side is working then I expect the problem is with the valve that controls the cooling on the other side.
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And yes, after 15 days the dealer finally diagnosed that the fault was with the actuator; well the diagnosing took a few hours, it was waiting for them to diagnose that took 15 days.

They will replace the actuator on the 12 Dec for a week, and we will miss our SE for 5 days.

And also since they will take out the dash, I now feel that our SE is going to be violated.

And we only had the SE for a year and 3 months, the dealer said we are the only one who had this issue; I feel disappointed, 1st it arrived without the HK and now this. The dealers comment of, “that is why we have warranties” is not comforting at all.
 
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