Run capacitor
Common no-start and weak-compressor failure point. Match the microfarad and voltage rating.
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 | Match to unit model number |
| Defrost sensor | Clip-on type - confirm placement on tube |
| Reversing valve | Match refrigerant and tonnage |
| Run capacitor | Dual-capacitor - check both sections |
| Contactor | Check for pitted contacts |
| Low-pressure switch | Match pressure setpoint |
Technician Tips
Goodman furnaces use a simple LED flash system on the control board. The diagnostic LED is usually visible through the blower compartment window. Count the flashes between pauses — that’s your error code. One flash = normal operation. Two flashes = pressure switch fault. Three flashes = limit switch. Four flashes = flame sensor. Goodman flame sensors are notorious for carbon buildup — cleaning with emery cloth every 2-3 years prevents most lockout calls. The control board on GMS8 and GMSS9 models is particularly sensitive to voltage fluctuations — if you see multiple different codes, check the transformer output (should be 24VAC ±10%).
Prevention: Install a whole-house surge protector on the furnace circuit to prevent board damage from power spikes.
Need Replacement Parts?
Before ordering, match the HVAC part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
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.