Goodman Furnace 4 Flashes [Solved]

Are you dealing with a Goodman furnace flashing 4 lights? If so then this is a perfect guide for you. We’ll walk you through possible causes for these flashes, and how to fix them. 

A Goodman furnace 4 flashes is an error code that applies that the high limit switch or rollout switch is open. This is commonly  due to overheating.

The common causes for overheating  include dirty filter, blocked return air grille, dirty evaporator coil (if equipped with a/c), restricted air flow, dirty blower wheel or blower not operating. Sometimes a defective limit switch could be the problem.

Read also: Goodman Furnace 3 Flashes

Please also note that many times this problem can be intermittent in which case the limit switch resets automatically as the furnace cools down.

 And that could actually mean  that it’s actually overheating, and the time it takes to shut everything down and reset is allowing it to cool down and reset.

Let’s look at these common causes for the 4 flashes on your Furnace:

Read also: Goodman 7P1 Code is 1dL Code Read Backwards

Possible Causes for 4 flashes on a Goodman furnace

Possible Cause	Fix
• Insufficient conditioned airover the heat exchanger.Blocked filters, restrictiveductwork, improper	• Check filters andductwork for blockage.Clean filters or removeobstruction.
circulator blower speed, orfailed circulator blower.	• Check circulator blowerspeed and performance.Correct speed or replaceblower if necessary.
• Misaligned burners, blockedflue and/or air inlet pipe, orfailed induced draft blower.	• Check burners for properalignment.• Check flue and air inletpiping for blockage,proper length, elbows,and termination. Correctas necessary.• Check induced draftblower for properperformance. Replace, ifnecessary.
• Loose or improperlyconnected wiring.	• Tighten or correct wiringconnection
Cracked heat Exchanger	Consider professional maintenance

Troubleshooting steps for Goodman Furnace 4 Flash Code (Primary Limit Circuit Open)

As I mentioned earlier, if your Goodman furnace is displaying a 4 flash code, indicating that the primary limit circuit is open, there are several potential causes for this issue. 

Follow these steps to troubleshoot and resolve the problem:

Read also: Goodman Furnace f02 code [Fixed]

Check the Air Filters

A dirty or clogged air filter can restrict airflow, leading to overheating. Turn off the furnace and locate the air filter.

If it’s dirty, replace it with a clean one. Make sure to regularly replace or clean the air filter every few months.

Read also: Goodman Furnace Solid red light [Solved]

Inspect Return Air Grilles and Registers

You may have to check the registers. If they are closed they could block air flow.

Blocked or obstructed return air grilles and registers can prevent  proper air circulation. Ensure that all return air pathways are clear from obstructions such as furniture, curtains, or other objects.

Restricted airflow due to closed or obstructed vents can also trigger overheating. Ensure that all supply and return vents are open and unobstructed to allow proper air circulation throughout your home.

Examine the Evaporator Coil (if equipped with A/C)

A dirty evaporator coil can restrict  airflow and cause overheating. If your furnace is equipped with air conditioning, check the evaporator coil and clean it if necessary.

Proper airflow over the coil is essential for efficient operation.

Check the Blower Operation

Ensure that the blower is operating properly. Turn on the furnace and set the thermostat to [fan  only trigger the blower fan.

If the blower does not turn on, there may be an issue with the blower motor or capacitor.

Test the Limit Switch

The primary limit switch is an important safety component that prevents overheating. The primary limit switch  is located on the partition panel and monitors heat exchanger compartment temperatures.

 It is an automatic reset, temperature sensor. The limit guards against the overheating resulting from insufficient air passing over the heat exchanger

 If none of the above steps resolve the issue, the limit switch might be faulty.

Cracked Heat exchanger  

A 4 flash on your Goodman  furnace could also be due to  a crack in the heat exchanger allowing the hot heat chamber air to blend with household air. 

When this happens, it  can always  trip the limit switch .

If you think  you may have a crack in the heat exchanger, consider a thorough furnace service done and let tech know about the problem you have dealt with

Final thoughts

In  summary, if you have a 4 flash code on a Goodman Furnace, either one of the following  things is at play:

1.  Low or no airflow across the heat exchanger, 
2.  Defective limit switch in which case can wrongly  signal the control board that the temperature in the combustion chamber is too high.

More resources: https://www.questargas.com/ForEmployees/qgcOperationsTraining/Furnaces/Goodman_%20GMV9_GCV9.pdf