Carrier Weathermaker 9200 Code 31 Pressure Switch

[dgp]

I have a Carrier Weathermaker model 9200 which is throwing an error code 31 for the pressure switch.  After researching a bit online I found that one of the drain lines could be clogged.  I pulled all three lines and they were fine, they didn't have any backed up water and I could blow through them.  I then checked the fan motor which appears to be spinning fine when the system in on.  It spins freely by hand when the system is off.  

 

Up in the furnace window I never see the glow of the starter.  It apparently never gets to that point in the startup.

 

Any thoughts?

 

Don 

[smee123]

Could be you have a bad pressure switch?

Can you ohm it out to see if it makes?

[dgp]

I disonnected the pressure switch leads and connected the ohmmeter leads.  I set the instrument to Ohms at 200 with a reading of "0L" when the system is off.  After turning the system on the motor began to spin and the ohmmeter spiked then settled on .2.  Am I testing the switch properly?  If so, the low reading means I need a new switch?

 

Thanks,

Don

[dgp]

Additionally, I checked the upstairs unit which is functioning correctly.  The pressure switch measured "0L" when off, then the ohms went to 20 (setting 200) back to 0L then up to 30.   It sounds like my pressure switch is bad.

 

Don

[Bullstok]

Junk in the intake pipe. Junk in the exhaust pipe. (Leaves, animals, wasp nests, etc). Bad pressure switch. Cracked pressure switch tubing. Loose wiring connections to switch.

A lot of the time clogged traps or drain tubes will cause water to back up into the inducer fan and make a water wheel out of it. You can usually hear the gurgle.