31
Moderate
Carrier · Central Air Conditioners & Furnaces
Pressure Switch Stuck Closed
Quick Answer
Error code 31 on your Carrier Central Air Conditioners & Furnaces means: Pressure Switch Stuck Closed. This is usually fixable — see the step-by-step guide below.
Likely Causes
How to Fix It
1
Disconnect the pressure switch hose and verify the switch opens (use a multimeter for continuity)
2
Inspect the hose for trapped water or condensation and drain if needed
3
Verify the correct pressure switch is installed by comparing part numbers to the wiring diagram
4
Replace the pressure switch if contacts are welded closed
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
Pressure switch tubing
Hose clamps
Related Error Codes