This paper is based on a study of heat pump compressor life initiated in 1985 in Alabama. Data from a heat pump maintenance contract program that has been in existence for nearly two decades provided information on up to the first 10 years of operation of nearly 18,000 heat pumps from seven major manufacturers. Major findings include the following:

1. Overall, 59% of all heat pumps in the data base were still operating on their original factory-installed compressors after 10 years.

2. Service life of original factory-installed compressors was beyond 10 years but could not be determined precisely because maintenance information was not available beyond age. Extrapolation of the data indicates a median life of approximately 13.5 years for all original compressors as a group.

3. Service life of first replacement compressors (second compressors) was at least 8.9 years, and probably longer.

4. Over the 20-year median service life of total heat pump systems determined from an earlier study, the average heat pump owner can expect to replace the compressor no more than once.

5. Recently installed heat pumps demonstrate markedly lower compressor failure rates than the averages presented here.