I own rental property being ran by an management agency. They are constantly contacting me about HVAC problems. The HVAC company responds that the evaporator coils were clogged and are cleaned. The management agency is aware they should routinely replace the filters. What are the long term implications to the heatpump of continually clogging the evaporator coils?

Donel

Fire the managment company they are not doing their job. Air filters in a year round operating system such as a heat pump should be changed at least four times a year. The filters should be a better quality then that of a cheep fiberglass type. Those should be changed once a month. Also they should be properly fit into the air-stream. So no air flows around them.

If the coils were dirty enough to be cleaned. Filters were not changed enough or do not fit right.

As far as any damage. Lack of air flow is the biggest killer of HVAC systems there is. Heat Pumps included.
The system is not able to move enough air through the indoor air coil thus the refrigeration action cannot complete itself properly. This causes wear and tear on the compressor as minute amounts of liquid refrigerent gets back to it. You cannot compress a liquid, so the valves within the compressor take a beating. Higher temps occur within the compressor as well. This causes the windings of the interior compressor motor to heat up and slightly burn. This can cause failure of the unit. heat pumps tend to fail more often then regular AC only units because of poor air failure.
Cost also go up as the emergency heat needs to operate more because your not delivering the heat that the pump is supplying. This can result in possible fire if the interior thermostat that protects against over heating coil fails.
Hope this helps.