I had a 190E that did that on a trip through the mountains. Uphill over a certain altitude was full heat. Turn it off, crest the hill and turn it back on, normal operation. Sorry, but I never found out what caused it. We don't have any mountains in FL so it was never an issue again. Hope you find it.

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Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
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