During a winter cave diving expedition several of the participants experienced regulator freezing. The air in the cylinders was analysed after the expedition and was found to contain a higher than advised level of moisture. The probable cause of this was use of an electrically-powered compressor indoors with the air intake taking air from inside the building. Because of all the wet equipment spread out to dry in the building humidity was high and this depleted the filter material of the compressor much faster than usual. A compunding factor may have been ingress of snow into the first stage while kitting up - in windy condition with snow blowing around its hard to prevent this.
Think carefuly about where you position the air intake of a compressor even if it is electrically powered and there are no exhaust gases from the engine to consider. Modern environmentaly sealed regulators should be able to function properly even in winter conditions so if freezing occurs (especially more than once) do not continue to dive without tracing the cause. Change filter material more regularly than the manufacturer recommends if the compressor is used under less than ideal conditions for example high humidity. If possible screw the regulator into the tank before transport to the cave to prevent any ingress of moisture during ktting up.