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Bryant Plus 90 Code 33 to 13 but doesn't seem to be the limit switch.

So I have this Bryant Plus 90 that is blowing cold air continuously. 

Last night I opened it up.  I found 1 flame rollout sensor on the side of the burner box and then the limit switch that goes in to the heat exchanger.  I tried pushing the button on the FRS with no success.  Next I pulled the two red wires off and jumped them, no success.  I used a meter and verified continuity and replaced the wires.

NExt I pulled the wires off the auto-resetting limit switch and jumped them with no result.  I tested it for continuity and my meter read 508.  Weird to me because usually it shows 1 for open circuit and 0 for closed.

So I set my meter on 200Vdc and tested for voltage across the red wires.  I got 0 volts in each place.  Then I went to the Control board and found where the red wires come out.  I found terminals that I could put my probes on and still got 0 volts. 

This leads me to the question of what am I missing? 0 volts tells me that there is an open in the circuit but the circuit is closed at the two interruption points I identified.  is there a third interruption point I missed?


  • Tim McElwain
    Tim McElwain Member Posts: 4,480
    The system you have

    is 24 volts so I would set the meter on AC volts to start with.
  • hheaddon
    hheaddon Member Posts: 10
    more limits

    I think if you follow the wiring diagram, you will find another limit inside the burner enclosure box.  When I worked on those, most of the limit wires were red and just made a big loop thru them all then back to control board. Depending on the age you may want to get a carrier / Bryant tech to check this out.