Most of us living in Arizona don't run our heat very often. However, it's still important to do regular maintenance on your heat pump... especially since your heat pump also cools your home in the summer months! Although heat pumps and air conditioners function differently, they both produce condensation as they cool. This condensation collects in a drain pan, and is then drained out through the condensate lines. These condensate lines can become clogged, leading to a significant risk of water leakage, water damage and mold. Having your home's heat pump or air conditioner serviced regularly can help to avoid much more expensive repairs in the future.
The picture below shows a heat pump's primary drain pan, which is full of rust and other crud indicating improper drainage. And yes, "crud" is a technical term!