Here’s a true story, from guy on a forum that subtly illustrates the essence of troubleshooting. The young man went to work as a beginner for a residential service company and spent a year or two learning something about residential systems. Then, he changed jobs and was immediately given work orders for commercial equipment and was struggling.
He came on the forum one day and posted, “I spend my days trying to figure out why something isn’t working right when I don’t know how it’s supposed to work, when it is working right.”
His single sentence sums up why some techs can troubleshoot effortlessly and others struggle. If you don’t know what a machine is supposed to do, you can’t begin to evaluate its operation and recognize a problem.
Here’s a practical definition of troubleshooting:
Comparing the actual operation of a system to the expected operation of the system and recognizing symptoms of unexpected operation.
In the case of heat pumps, ‘expected’ operation is design operation. When the thermostat calls for heat or cool, the electricity flows through the air handler blower, compressor and condenser fan motors and they run. The reversing valve switches to the proper position to divert the refrigerant flow in the correct direction, the refrigerant flows through the two coils, either taking in heat in the evaporator or releasing heat in the condenser as a result of the air, flowing through the coils.
When all the ‘flows’ take place, per design, the system either cools or heats as it should.
The thing is, troubleshooting is not a learned skill. You can’t find a book that will teach you all aspects of troubleshooting heat pumps. The skill comes naturally as a result of learning how stuff works and that is what this blog will concentrate on providing. There will be examples of field problems and steps involved in reaching a diagnosis but without some understanding of a few science principles and a thorough understanding of how heat pumps are supposed to work, examples of field problems with solutions will only teach you how to evaluate and diagnose a single specific situation. And I can’t provide every possible situation that might come up. I’m a near 40 year veteran in this business and still see things I haven’t seen.
The “Fundamentals” category covers the science stuff you need to know which includes boiling point, heat transfer and the gas laws.
