43
Moderate
Carrier · Central Air Conditioners & Furnaces
Pressure Switch Calibration Fault
Quick Answer
Error code 43 on your Carrier Central Air Conditioners & Furnaces means: Pressure Switch Calibration Fault. This is usually fixable — see the step-by-step guide below.
Likely Causes
How to Fix It
1
Measure actual pressure differential at the pressure switch with a manometer during inducer operation
2
Compare measured pressure to the switch rating stamped on the device
3
Inspect flue and intake pipes for partial obstructions
4
Check inducer motor performance by measuring amperage and comparing to rating
5
Contact a licensed HVAC technician for pressure switch calibration or replacement at high-altitude installations
Pro Tip
This fix requires some technical knowledge. If you're unsure about any step, consider contacting support or a qualified technician.
Parts You May Need
Pressure switch (altitude-specific if applicable)
Inducer motor assembly
Vent pipe components
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