There is steam rising from my heat pump outdoor unit. What is wrong?
All heat pumps have a defrost cycle built into them to eliminate the normal build-up of frost and ice that occurs during the heating cycle. The typical design, a time and temperature defrost, operates in the following manner. A sensor measures the operating temperature of the outdoor coils, if they are below freezing, an internal clock will send the unit into defrost every 90 minutes (actual running time). During defrost, the outdoor fan stops, the compressor keeps running and the unit switches over to the air conditioning mode. This causes the outdoor coils to heat up, melting off any frost and ice that may have accumulated. The defrost cycle will typically last until the coils reach a predetermined temperature, or 10 minutes, whichever comes first. During this defrost period you may see clouds of what looks like smoke pouring off the outdoor unit. This is actually steam, a perfectly normal result of the heated coils, which will be even more pronounced during rainy or humid conditions
