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MY2012 Premium/Bose/Leather/Nav, assembled August 2011, 55K miles (75% EV) - We've had a pretty hot summer here in Oklahoma City. I'd been noticing that the TMS (thermal management system) seemed to be working a lot more than the previous three summers I've owned the car, garage can get well over 100 degrees.
Anyway, got a CEL, Torque identified it as P0534 - basically the battery not being cooled enough. A few days later, got an email from OnStar saying there was a problem with the battery that needed to be looked at immediately (strangely, no in-dash vehicle message?!) Took it to the dealer and they said the freon was VERY low. I was skeptical because the AC in the cabin is ice cold even when over 100 degrees outside. They found no leaks, did an evacuate and recharge and it's all fixed now. Got it home, hooked up to the 240V EVSE and was very happy to hear practically nothing from the TMS, even after charge completed. Obviously, the correct level of freon makes the TMS function MUCH more efficiently. I hadn't realized how much the TMS had slowly increased its workload with the lower freon level.
Moral of the story. If you feel like your TMS is working harder than it used to, get your freon level checked. It is possible to have great cabin AC and at the same time not have enough refrigerant to properly cool the battery.
Anyway, got a CEL, Torque identified it as P0534 - basically the battery not being cooled enough. A few days later, got an email from OnStar saying there was a problem with the battery that needed to be looked at immediately (strangely, no in-dash vehicle message?!) Took it to the dealer and they said the freon was VERY low. I was skeptical because the AC in the cabin is ice cold even when over 100 degrees outside. They found no leaks, did an evacuate and recharge and it's all fixed now. Got it home, hooked up to the 240V EVSE and was very happy to hear practically nothing from the TMS, even after charge completed. Obviously, the correct level of freon makes the TMS function MUCH more efficiently. I hadn't realized how much the TMS had slowly increased its workload with the lower freon level.
Moral of the story. If you feel like your TMS is working harder than it used to, get your freon level checked. It is possible to have great cabin AC and at the same time not have enough refrigerant to properly cool the battery.