31
Rheem
Pressure Switch Did Not Close or Reopen
Status LED flashes 3 short and 1 long (31); furnace may not start or may shut down early
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Blocked vent or intake, Condensate blockage in collector box, Weak inducer motor, Faulty pressure switch
How to Fix / Troubleshooting
Safety first: Turn off power and gas before working on venting or condensate systems.
- Check PVC vent and intake: Inspect all accessible vent piping for sags, separations, or blockages. Clear any obstructions at terminations.
- Inspect condensate drain: For high-efficiency Rheem furnaces, check the condensate trap and hoses for clogs or kinks. Clean the trap and flush with water.
- Verify inducer performance: Listen for smooth inducer operation. If noisy, slow, or not starting, test voltage to the inducer and replace if defective.
- Test pressure switch: Use a manometer or multimeter to verify the switch closes at the specified negative pressure. Replace if it fails to close with proper inducer operation and clear venting.
Do not drill or modify pressure switch ports; use only OEM-rated switches.
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Repair Difficulty
Hard
4/5
Required Part
Pressure Switch
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