If your heat pump is trying to tell you something, the first thing to pay attention to is the noise it's making. If you hear grinding, squealing, or banging coming from the heat pump, you'd be wise to call in a pro. Reduced performance in terms of either heating or cooling, energy bills that are much higher than normal, on-off cycling that's more frequent than you'd expect, and visible ice buildup on the outdoor unit are all warning signs that your unit needs attention. And then there's the not-so-nice issue of odors; strange smells when the heat pump is running could just be mold, but they could also signal something more serious.