Complete reference for all Hayward HeatPro and Summit heat pump error codes. Search by code or symptom to find the cause and fix.
The Hayward HeatPro is a popular pool heat pump line spanning models from 50,000 to 140,000 BTU. The Summit series uses the same core refrigerant circuit with some different error code designations on the display. Both platforms display error codes on the unit's front panel when a fault condition is detected.
Unlike gas heaters, heat pump error codes frequently relate to refrigerant pressure, ambient temperature, or water flow rather than combustion. Understanding the difference between a normal operational state (like dEF defrost mode) and a genuine fault (like LP low pressure) prevents unnecessary service calls and helps technicians come prepared.
The HeatPro platform uses HI for high pressure faults, while the Summit platform uses HP for the same condition. Similarly, PO (HeatPro) and OP (Summit) both indicate compressor overload. The underlying causes and diagnostics are identical across both platforms.
Several HeatPro error codes require EPA 608-certified refrigerant handling:
LP stands for Low Pressure and indicates the low-side refrigerant pressure switch has tripped. The most common causes are a dirty evaporator coil (the large finned section that faces outward), low ambient temperature causing the refrigerant to behave abnormally, or an actual refrigerant leak. Clean the evaporator fins with a gentle coil cleaner and rinse from the inside out. If the code returns, have a certified technician check refrigerant charge and inspect for leaks.
dEF is normal operation, not an error. When ambient temperatures drop below approximately 50°F, the evaporator coil can frost over. The HeatPro enters a defrost cycle to melt the frost and restore efficiency. During defrost, the unit may temporarily stop heating and the display shows dEF. This cycle typically lasts 5–10 minutes. If the unit is frequently entering defrost in warm weather, the evaporator coil may be dirty or there may be an airflow restriction.
A Flo error with the pump running usually points to one of four things: (1) the pump is running too slowly (common with variable-speed pumps set to a low RPM program), (2) the filter is dirty enough to restrict flow, (3) a valve is partially closed in the plumbing path through the heat pump, or (4) the flow switch itself has failed or its wiring is damaged. Check that your VS pump is running at a speed that produces adequate flow through the heat pump. The HeatPro requires a minimum flow rate of approximately 20–25 GPM depending on model.
For most error codes, power cycle the unit at the breaker: turn off the breaker, wait 30 seconds, and restore power. The HeatPro should attempt to restart. If the error returns immediately, the underlying condition has not been resolved. Do not repeatedly reset a unit without addressing the root cause, as this can mask a developing refrigerant or electrical problem.
A blank display typically means no control power is reaching the unit. Check the circuit breaker first. Verify the disconnect at the unit is in the on position. Check for a blown 5A control fuse on the unit's control board (common after lightning or power surge events). If voltage is confirmed at the disconnect but the display remains blank, the transformer or control board may have failed.
Yes. The HeatPro VS uses the same refrigerant circuit and error code set as the standard HeatPro. The variable-speed compressor adds the benefit of running at reduced capacity during mild weather, but the fault codes and diagnostic procedures are the same. One additional consideration: a VS model showing repeated LP or HI codes at specific compressor speeds may indicate a speed-related refrigerant balance issue, which requires a technician with variable-speed heat pump experience.
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