Avoid Costly Repairs: Troubleshooting a 3 Flash Code on Goodman HVAC Systems
Recently, I encountered a “3 flashing light” error code on my heating system. Familiar with these codes, I wasn’t surprised something was wrong. Unfortunately, my Goodman heater seems to develop issues every year. In my opinion, the quality of these units is subpar.
This year, in preparation for winter, I followed my usual routine. My Goodman heater doesn’t run after being idle all summer and requires me to bleed air from the system to start it up. Although there are no leaks and the pressure is correctly set, the heat of summer causes the propane to degrade, a common issue with lower-quality propane. HVAC vendors must profit handsomely from charging service fees for this simple task.
To get ahead of potential issues, I replaced flame sensors, and ignitors—all wearing parts. Burners typically last about 10 years, but flame sensors and ignitors can fail at any time. I inspect my burners annually. Replacing the flame sensor and ignitor before winter is a smart, inexpensive precaution. While you could keep spares on hand, changing them mid-winter when the heater fails is less ideal.
Having dealt with Goodman HVAC systems for years, I also keep a spare control board on hand. A local HVAC technician once quoted me $900 for a control board that I later purchased on Amazon for $60. Over the past 15 years, my Goodman heater has gone through three control boards. These high failure rates have pushed me to learn how to perform most repairs myself.
Understanding the “3 Flash Code”
On a Goodman system, a solid light on the control board indicates everything is fine. However, when the small motor begins clearing gas from the system, the board switches to a “3 flash” code and shuts down. This typically signals an issue with the pressure sensors. My unit has two sensors: one for the drip (evaporative) line and another for the flue.
Testing these sensors is straightforward. Use an ohm meter to check if the switches close when air flows through the hoses. Inspect the hoses for cracks or leaks as well. Both my sensors tested fine, but the system still failed to start.
Many online guides recommend using specialized equipment and performing intricate tests. However, if the sensors close the circuit, they are likely functioning properly. If the control board returns to a solid light after shutdown, it is also likely fine. The real issue often lies elsewhere.
Check the Flue Pipe
HVAC technicians may suggest a clogged vent line or other issues, but they rarely emphasize the importance of checking the flue. A blocked flue creates back pressure, shutting the system down.
In my case, the problem was a yellow jacket nest blocking the flue’s exit vent. Removing the rodent guard at the flue’s end revealed the nest, which I cleared out. Afterward, the heater fired up perfectly. Surprisingly, I found no online resources that mentioned this issue, so I’m sharing it here: always check your flue pipe for obstructions.
A simple wasp nest could have cost me $250 in service fees, as most technicians would check the sensors first and only inspect the flue as a last resort. Going forward, checking the flue will be the first step in my winter maintenance routine.
Final Thoughts on Goodman Heaters
While Goodman heaters seem to be prone to frequent issues, I’ve learned to prepare by keeping spare parts on hand, including a control panel, ignitor, flame sensor, and pressure switch. These cover most common problems and can get your system running quickly.
To ensure a long-lasting system, inspect the burners annually for corrosion or cracks, verify proper condensation drainage in vent lines, and maintain the blower motor. After running all summer with your air conditioner, the blower fan may need cleaning and lubrication.
Good luck with your HVAC system, and I hope this guide helps you avoid costly repairs!
Disclaimer:
Do not attempt a repair on your HVAC system if you have no idea what you are doing. Call one of those qualified professionals to do the work. Mistakes with these units can cause death by gas exposure, electrocution or by fire. Spending a few hundred bucks is certainly worth it to have a qualified professional work on your system.
