Goodman Furnace 3 Flashes [Solved]

Is your Goodman Furnace flashing 3 times and you don’t really understand where the problem is? Don’t worry. In this troubleshooting guide, we’ll look at the possible causes of the problem and walk you through practical solutions to get your furnace back up and running.

A Goodman Furnace with 3 blinking lights is code error that indicates that a pressure switch is not closing or a stuck open pressure switch. Now, a several things that can prevent the pressure switch from closing.

 Lets look at some of these issues in the chart below

Read also: Goodman Furnace Solid Red Light On But Furnace Not Working [Solved]

Possible causes for Goodman Furnace 3 flashes and Solutions

Pressure switch hose blocked, pinched orconnected improperly.Inspect pressure switch hose. Repair, ifnecessary,
Blocked flue and/or inlet air pipe, blocked drain system, or weak induced draft blower.Inspect flue and/or inlet air piping for blockage, proper length, elbows, and termination. Check the drain system. Correctas necessary.
Incorrect pressure switch setpoint or malfunctioning switch contacts.Correct pressure switch setpoint orcontact motion.
Loose or improperlyconnected wiring.Tighten or correct wiring connection.

Troublehooting A Goodman thermostat with 3 blinking lighs 

Check Inducer Motor Operation

Start by confirming whether the inducer motor is running. The inducer motor is responsible for creating the necessary vacuum to close the pressure switch.

 If the inducer motor isn’t operational, it won’t establish the required vacuum.

If the inducer is not running, you will not get heat, test the inducer with  your multimeter and see if you  are getting 120vac to the inducer.

If you are not getting power to the inducer make sure  all the limits are closed. Sometimes an open limit will keep it from getting power.

Tap on the pressure switch and make sure it is not stuck closed.

Read also: Goodman Furnace code f02

Inspect Pressure Switch Hose and Connections

The pressure switch is activated by the vacuum created by the inducer motor. 

Ensure that the hose connecting the pressure switch is not blocked, pinched, cracked, or improperly connected.

 Any impediment to the vacuum flow can result in the pressure switch not closing properly.

Examine Flue and Induced Draft Blower

Check for any blockages in the flue or a weakened induced draft blower. 

The induced draft blower assists in creating the vacuum necessary to close the pressure switch. 

An obstruction in the flue or a weak blower can hinder this process.

Read also: Solid Red Light On Furnace Circuit Board [Solved]

Verify Pressure Switch Setpoint and Contacts

Make sure the pressure switch is set to the correct setpoint. Additionally, inspect the pressure switch contacts for any malfunction. Incorrect settings or faulty contacts can prevent the switch from closing.

Inspect Wiring Connections

Loose or improperly connected wiring can disrupt the signal between components. 

Examine all wiring connections related to the pressure switch and inducer motor to ensure they are secure and properly connected.

Read also: Carrier Furnace Light Blinking 3 Times [Solved]

Check for Blockages and Water Backup

Ensure there are no blockages in the vent or intake pathways. If your furnace has a drain connected, make sure there’s no water backed up in the hoses. 

Both blockages and water backup can hinder the vacuum process.

Test Pressure Switch Functionality:

Disconnect the rubber hose from the inducer but keep it attached to the pressure switch. Call for heat at the thermostat and then manually create a vacuum by sucking on the hose. 

Listen for the audible click of the pressure switch and observe if the burners ignite. This test helps determine if the pressure switch is functioning correctly.

Bypass Pressure Switch:

With the inducer motor running, consider bypassing the pressure switch temporarily using a jumper wire. This mimics the switch being closed. If the furnace ignites, it suggests a faulty pressure switch.

Specialized Vacuum Tests

Using a vacuum manometer or a magnehelic gauge, measure the vacuum between the inducer and the pressure switch. 

This test checks if the vacuum is within the required range to close the switch. 

These tools may require professional expertise, so consulting an onsite technician might be necessary.connected wiring.

Are pressure switches and limit switches all good?

If the pressure switches and limit switches have continuity, you  may have a defective circuit control board.If that’s the case.

 You might have to replace  circuit control board, but call a tech to verify t verify this as controls boards are really expensive.

Final thoughts

In summary, 3 flashes on a goodman furnace is caused by a problem with pressure switches. I hope that you have found a solution to the problem after reading this guide. 

If you are still struggling with finding out what the problem really is i recommend you call in tech for help.

Thanks for reading.

More resources:

Similar Posts