Goodman GPH Series Packaged Unit Error Codes
Goodman GPH packaged heat pump units communicate faults via an LED on the control board. Count LED flashes between 3-second pauses. The board stores the last 5 fault codes — press the diagnostic button once to scroll through stored faults.
GPH Flash Code Table
| Flashes | Fault Description | Common Cause | Action |
|---|---|---|---|
| 1 | Normal operation | No fault | N/A |
| 2 | Low-pressure lockout | Low refrigerant, frozen coil | Check charge, defrost coil |
| 3 | High-pressure lockout | Dirty coil, failed condenser fan | Wash coil, check fan |
| 4 | Open high-pressure switch | Refrigerant overcharge | Check subcooling |
| 5 | Open low-pressure switch | Low charge or refrigerant leak | Find leak, check TXV |
| 6 | Compressor overload | High amperage, failed capacitor | Check cap, contactor, voltage |
| 7 | Defrost lockout | Defrost board failure or sensor fault | Check defrost sensor |
| 8 | Reversing valve fault | Stuck reversing valve | Check 24 VAC to RV solenoid |
| 9 | Control board fault | Internal board failure | Replace control board |
Most Common GPH Faults
2 Flashes — Low-Pressure Lockout
Common in cold weather when outdoor coil ices over. Check airflow across the outdoor coil. Low refrigerant charge also triggers this — measure superheat and compare to charging chart.
3 Flashes — High-Pressure Lockout
Dirty condenser coil is the most frequent cause. On packaged heat pumps, the coil is exposed year-round. Wash thoroughly with coil cleaner and verify condenser fan is running.
7 Flashes — Defrost Lockout
If the unit fails to defrost, ice accumulates on the outdoor coil, eventually tripping the low-pressure switch. Check defrost sensor clip placement (must contact refrigerant tubing) and defrost termination thermostat continuity.
8 Flashes — Reversing Valve Fault
Check for 24 VAC at the reversing valve solenoid in heating mode. A stuck valve may be freed by cycling power. If the valve body is iced or temperature differential is absent, replace the valve.
Parts Commonly Needed
| Part | Notes |
|---|---|
| Defrost control board | Amazon | Match to unit model number |
| Defrost sensor | Amazon | Clip-on type — confirm placement on tube |
| Reversing valve | Amazon | Match refrigerant and tonnage |
| Run capacitor | Amazon | Dual-capacitor — check both sections |
| Contactor | Amazon | Check for pitted contacts |
| Low-pressure switch | Amazon | Match pressure setpoint |
Pro tip: Goodman GPH packaged units have the reversing valve energized in cooling mode. If you’re testing in heating mode and the valve is de-energized, confirm the solenoid is not stuck energized from a previous short.
Related Articles
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- Goodman 2 Flash Error Code — Causes & Fix
- Goodman 3 Flash Error Code — Pressure Switch Stuck Open Fix
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