Strange Heat Off Problem Solved?

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Sep 24, 2019
Hi all,

Thought I'd share an observation.

I've been baffled for a week or two why it seemed like when I turned the HVAC on, but with Heat Off (and no Auto) the car (2019 Premier) would still blow warm air (with associated display of increased power draw and reduction in GoM range). This issue is reported elsewhere on this forum, but that thread is locked (in the Ask Chevrolet area).

Anyway, today it dawned on me I had seen an Auto Defrost option in the settings when I was exploring the settings after I first got the car. I checked and sure enough that option was ON, which I presume was causing the car to want to blow warmer air on the windscreen now that the humidity is higher to prevent fogging. I went in and set Auto Defrost to OFF, and the HVAC appears to now allow having the Heat actually OFF.

I haven't had a chance to repeat this experiment or confirm it, but thought I'd share in case anyone else experiencing this wants to try to corroborate.


Yep, had exactly the same experience. Heat would come on at odd times. Turned auto defog off and that fixed it.