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Hi guys, can someone answer this : is it possible that the car blows freezing air inside the cabin even if the AC is closed when driving in hot temperatures because of the conditioning / BTMS trying to cool down the battery temperature ?
I couldn’t find any info regarding the way BTMS works on the Bolt EV. 🤷🏻‍♂️
 

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IIRC, I noticed this on my Gen I Volt. I assumed the cabin heat exchanger was on the same coolant circuit as the BTMS without a diverter valve so if air was flowing through the vent system, the cabin got some air conditioning. Can't say that I've noticed this on the Bolt. If it's warm enough to cause the BTMS to cool the battery I will have the AC on anyways.
 

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While the battery coolant system and the cabin air-conditioning system share the same "compressor", they have separate "evaporators" and coolant loops, and run independently. The BTMS (which both heats and cools) runs quite independently of the cabin heating and cooling.

There are nine high-voltage modules in the Bolt EV: 1) the rechargeable energy storage system (RESS) {the HV battery}, 2) the high power distribution module (HPDM), 3) the single power inverter module (SPIM) {changes HVDC to HVAC [and contains a "rectifier bridge" for regenerative recharging]}, 4) the traction motor (MG1), 5) the accessory power module (APM) {changes 355 VDC to 14.5 VDC to recharge the 12 VDC battery and run the accessories}, 6) the on-board charging module (OBCM) {rectifies 120 VAC or 240 VAC and transforms it to 355 VDC}, 7) the air-conditioning compressor module (ACCM) {compresses the refrigerant [not the coolant] for BOTH evaporators [RESS loop and cabin A/C loop]}, 8) the battery heater (RESSH), and 9) the heater coolant heater (HCH) {heats the "coolant" fluid loop to the cabin heater core}. The single battery "coolant" loop fluid runs through both a heater and a cooler, with the BTMS turning on whichever is needed. [Info based on John Kelly's wonderful WeberAuto YouTube series.]
 

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Hi guys, can someone answer this : is it possible that the car blows freezing air inside the cabin even if the AC is closed when driving in hot temperatures
Make sure the default "auto defrost" is turned off in settings. There is a temperature sensor, and a humidity sensor, located up behind the rear view mirror. If the auto defrost system detects conditions that might cause windshield fogging, both the heater and AC will run.
 

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IIRC, I noticed this on my Gen I Volt. I assumed the cabin heat exchanger was on the same coolant circuit as the BTMS without a diverter valve so if air was flowing through the vent system, the cabin got some air conditioning. Can't say that I've noticed this on the Bolt. If it's warm enough to cause the BTMS to cool the battery I will have the AC on anyways.
I've noticed the same behavior in the Bolt EV with the cabin fans on.
 

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Make sure the default "auto defrost" is turned off in settings. There is a temperature sensor, and a humidity sensor, located up behind the rear view mirror. If the auto defrost system detects conditions that might cause windshield fogging, both the heater and AC will run.
This! Once I disabled auto-defrost, I stopped experiencing heating and cooling when heat\AC was off.
 

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Discussion Starter #7
Thank you guys, you are the best !
 
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