43
Ducane
Two-Stage Pressure Switch Fault
Code 43, low stage or high stage pressure switch fault on two-stage Ducane furnace
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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
Incorrect pressure switch for application, Vent length exceeding Ducane specifications, Weak inducer on high stage, Blocked vent or intake
How to Fix / Troubleshooting
Safety first: Turn off power and gas before working on venting or pressure switches.
- Step 1 – Verify venting: Measure total vent length and number of elbows. Compare to Ducane installation manual limits. Shorten or correct venting if out of spec.
- Step 2 – Inspect both pressure switches: Ensure tubing is correctly connected to low and high stage switches and not crossed.
- Step 3 – Clear obstructions: Check terminations for blockages and clear as needed.
- Step 4 – Professional evaluation: A technician should verify correct switch ratings and inducer performance.
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Repair Difficulty
Hard
4/5
Required Part
Two-Stage Pressure Switch Set
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