Outdoor part of system unit has one condensate drain line that drains when unit is in AC mode. One on opposite side of unit that drains when unit is in Heat mode. Temps in mid 20's for last 24 hours. This afternoon I noticed a big icicle hanging off of end of heater side drain tube earlier today. Thought I had freed the blockage of ice in the tube. Checked it again a few minutes ago, and the whole tube is frozen now. Heater working in room (mancave) fine. Only a light frost on coils on back side, not a sheet of ice. Front side clear and air flowing out from fan. Looks like water in the pan has frozen as well as best I could see in with flashlight.

Is this situation a problem? Had this unit installed since the big freeze of '01, and not really familiar with these units.

TIA OB.

Heater shouldn't condense or produce water and shouldn't run in this cold

You shall survive

In heat mode, the condensation should freeze to the outdoor coil, the heat pump will go into defrost most to clear the coil. There should be no condensation in heat mode. You should see a nice cloud of steam in defrost mode.