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Espo 03-17-2012 12:07 PM

Carrier Weathermaker 9200 error code 31
Just yesterday I received an error code 31 with my Carrier Weathermaker 9200. I had the unit installed brand new back in 1999. I have been lucky over the past 5 years. However, during the first 2-5 years a lot went wrong; I had to replace about 5 Hot Surface Ignitors, 1 Pressure switch and another part that I think was called the gas valve unit. (The part had several S-shape bends; made up with 1Ē tubing; with several holes in it and at one end of the pipe there was a square control value unit,)

Now overnight, it just started receiving an error code 31. The heater stats up like normal and the exhaust blower (Item #6 under furnace components list) also starts up. However after about a minute of run time; the main blower does not start up and there is no flame visible in the sight window and then the red solid light starts blinking the error code 31.

Iím very mechanically inclined; But. Iím not sure how to test the following.

1. Inducer motor or start capacitor
2. Pressure switch and/or connection
3. Low inducer voltage
4. Obstructed pressure tubing

Can anyone please explain or point me in the right direction. I have been unable to work since last April do to taking care of my 78 year old mom and I need to fix this heater myself to save money.

how 03-17-2012 01:24 PM

I am assuming that fault code 31 is an air flow issue but the legend on your furnace door will verify this.
Anything that affects the air pressure through air intake, burner compartment, exchangers, inducer assy, the pressure switch, those hoses or the exhaust vent can cause that code..
The first thing to start to check is that all the small hoses connected to your inducer assy or pressure switch are crack and split free. Next check that the hoses are clear and water free. Next check for debris build up just inside the hose port inside the ID assy. Use a straightened paperclip to test 2 " inside it and to clear it if its obstructed.
The inducer normally gets tested with a manometer to check the pressure it creates at the hose bib. It might be listed on the ID assy in inches water column. A clear plastic tube attached to the ID hose bib which then drops down and loops back up beside itself and is half filled with water will usually work. When the inducer motor comes on, the total difference in height that is created in the two water levels in the water in that hose will give you the Inches water column that the inducer is producing.
Let us know what you find.

hvactech126 03-17-2012 01:45 PM

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