Goodman Error Code F04: Goodman Code F04 - High Limit Switch Open
How to Fix Goodman Code F04
- Step 1: Check and replace your air filter. A dirty filter is the most common cause. Use the filter size printed on the old filter to buy a new one.
- Step 2: Ensure all return air vents are open and not blocked by furniture or rugs. Good airflow is key.
- Step 3: Reset the furnace by turning off the power at the breaker for 60 seconds, then turn it back on. If the error returns, call a qualified HVAC technician.
How to Reset Goodman Code F04
- Turn off the furnace power switch, usually located on or near the unit.
- Turn off the circuit breaker for the furnace. Wait 30 seconds.
- Restore power at the breaker and flip the furnace switch back on.
- Set the thermostat to call for heat. If the error code returns after 2-3 ignition attempts, the fault requires repair.
Resetting clears the code from the display but does not fix the underlying fault. If the code returns after reset, proceed to the diagnostic steps above.
What Does Goodman Error Code F04 Mean?
The F04 error code on your Goodman furnace indicates that the high limit switch has tripped. This switch is a safety device designed to shut down the furnace if it gets too hot, preventing damage and potential fire hazards. When the furnace overheats, the high limit switch opens, cutting off power to the gas valve and blower motor. The furnace will then display the F04 error, indicating the problem. It's important to address this issue promptly, as repeated overheating can damage components and leave you without heat.
Common Causes
- Dirty air filter restricting airflow
- Blocked return air vents reducing airflow to the furnace
- Faulty blower motor not moving enough air across the heat exchanger
- Over firing of the burners causing excessive heat
- Defective high limit switch tripping prematurely
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Furnace displays F04 error | Measure voltage across the high limit switch terminals with the furnace off | 0 VAC (open circuit) |
| High limit switch is open | Inspect the physical condition of the heat exchanger for cracks or damage | Heat exchanger should be clean and free of cracks or warping |
| Heat exchanger appears OK | Measure the blower motor amperage while running | Amperage should be within the range listed on the motor nameplate |
| Blower amperage is low or normal | Check gas pressure at the gas valve | Manifold pressure should match the rating plate (typically 3.5" WC for natural gas) |
Applicable Goodman Models
Recall Notices
Issued: November 1, 2021
Affected models: Molded plastic evaporator coil drain pans in up-flow condensing gas furnaces
Drain pans can overheat, melt, and deform, posing a fire hazard. Recall expanded January 2024.
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| High Limit Switch | B13701-22 | — | Find Part |
| Blower Motor | — | — | — |
| Air Filter | — | — | — |
Related Codes on Same Models
Other codes that affect the same Goodman model families as F04.
| Code | Description | Severity |
|---|---|---|
| 1 | System Lockout | Warning |
| 2 | Pressure Switch Stuck Closed | Warning |
| 3 | Pressure Switch Stuck Open | Warning |
| 4 | Open High Limit Switch | Warning |
| 5 | Flame Sensed With Gas Valve Off | Warning |
| 6 | Open Rollout Switch | Warning |
| 7 | Low Flame Signal | Warning |
| 8 | Ignitor Error | Warning |
| CONTINUOUS | Reversed Polarity | Warning |
| STEADY-ON | Normal Operation | Info |