Cooling SystemQuestionCommunity Starter

A/C is cold while driving, warm at stoplights

QuattroLearner17Community StarterJun 29, 20262023 BMW M340i xDriveLas Vegas
2023 BMW M340i xDrive, about 48,000 miles. A/C gets properly cold on the highway but becomes noticeably warmer at long lights. It cools down again almost immediately once the car is moving. Could this still be a refrigerant issue or does that point more toward airflow/fans? If I fix it I'll come back and update the thread.
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2 replies

CruiseBuilderCommunity StarterCommunity StarterJun 30, 2026permalink
Ask what changed right before it started. Move a coil or plug on the 2023 BMW M340i if it's cylinder-specific and see whether the code follows. Save the big job until that test fails. Any freeze-frame data saved? I already checked the easy fluid levels.
NorthDailyCommunity StarterCommunity StarterJun 30, 2026permalink
Intermittent stuff lies if you only catch it once. Capture voltage while the 2023 BMW M340i is actually failing — after it restarts you've lost the clue. Save the big job until that test fails. On “a/c is cold while driving, warm at,” that was the fork that mattered for me. Write the result down so the next test isn't a repeat of the last one. I'd rather look cautious in this thread than stuck later.
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