Heat Pump Frost Ice BuildUp | HVAC-Troubleshooting

Heat Pump Frost Ice Buildup. Hi. I noticed that one of my outside heat pump condensing units was laboring throughout the night. This morning I found ice frost buildup on the heat pump condenser fins. I live in Tucson, Az. It has been colder than normal (below freezing) with a bit more moisture in the air than usual as of late.

Can you please tell me what causes this frost ice buildup, and how I go about rectifying it? Does this mean that the condenser pump is shot? I’m originally from the Midwest and have never experienced this before. What should I be doing? Thank you for your help. (more…)