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A usual operating temperature specification for allowed ambient temperature ranges, for the usual sort of AC Adapter, is 0 to 40 degrees C.
This means that having such an AC Adapter of the typical type and typical temperature range specification, makes it quite inadvisable to operate or use it in sub-freezing temperatures, period.
Problems might include wrong voltage applied to device, causing device failure, or AC Adapter failure to work properly in other ways or permanent failure of AC Adapter.
Some AC Adapters are designed for a greater temperature range, but those are specially made that way, for outdoor conditions.
If you will tell me your AC Adapter's maker or manufacturer, and model, I can look up specific specifications for it, as an individual and specific case.
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