Rheem Furnace Green Light Flashing Four Times – Pressure Switch Stuck Closed

About 1.5 years ago, my furnace stopped working.  At the time it was due to an inducer blower having burned out, causing a warning of “Pressure Switch Stuck Open”, with the warning of a green light blinking twice.

Today, we came back from a week vacation where we had the thermostat turned down.  When we turned up the thermostat, nothing happened.  Uh oh.  I went down to the furnace to see what was going on and found the green light blinking, but this time it was blinking four times, pause, then four more blinks, pause, four blinks, etc.

I looked up what that message meant and interestingly, it means “pressure switch stuck closed”.  Very similar to the problem I had the last time, but not the same.  I at first figured that perhaps the inducer blower had failed again, thinking that perhaps the much lower cost ordering it from Amazon meant it was an inferior product.  I went back through the same troubleshooting steps I did the last time, including pulling off the vacuum hose from the pressure switch, and blowing in and out gently to make sure I could hear the clicking noise.  It turns out, after doing that to the first pressure switch, everything starting working fine!

In the other post, I had included a video of someone showing how to test the pressure switch, so I’ll include that again here.  This time, that solution worked for me and got my heat going again.  Based on people’s comments, it appears sometimes the fix works for a while and sometimes it fails again shortly thereafter.  I’m assuming there is some kind of buildup on the switch causing it to stick and it will probably fail again at some point soon.  I’ll probably order a replacement switch so that I can avoid it failing again.  I’ll update this post when I replace the switch, or if it fails again before I can do that.

I am glad it was not the inducer motor again, as that was a $190 part.  The pressure switches appear to be closer to $40 each.

<update 12/21/19>
So two days ago, the same thing happened.  Our downstairs was very cold, the heater was not running in spite of the thermostat being set properly.  I went down to the furnace, and saw the same green light blinking four times, pausing, then blinking four times, etc.  I gently blew on the tubing again, and the furnace restarted without a problem.  Now that this has happened twice within one year, I just bought replacement pressure switches on Amazon.  I will probably just go ahead an replace them, rather than wait for it to fail again, in case it happens when I am out of town or some other inconvenient time.

One switch had the model number 42-24195-03 and was about $60 at Amazon.

The other pressure switch had model number 42-24196-04 and was around $35 on Amazon.

Both of my switches said “Honeywell” on them, yet I have a Rheem furnace.

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