3 blinks
Easy Fix
York · HVAC Systems (AC, Furnaces, Heat Pumps & Thermostats)
Pressure Switch Stuck Closed
Quick Answer
Error code 3 blinks on your York HVAC Systems (AC, Furnaces, Heat Pumps & Thermostats) 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 using a multimeter
2
Check the hose for trapped water and drain if present
3
Verify the correct pressure switch part number for the furnace model
4
Replace the pressure switch if contacts remain closed without applied pressure
Pro Tip
This is a common issue that most users can resolve without specialized tools. Try the first step before moving on to more complex solutions.
Parts You May Need
Pressure switch
Pressure switch hose
Related Error Codes