F2
York
Low Voltage / Thermostat Signal Fault
York air handler board flashes F2 and system will not start cooling
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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
Blown low‑voltage fuse on control board, Shorted thermostat cable, Miswired thermostat, Faulty thermostat
How to Fix / Troubleshooting
Safety: Turn off power to the air handler or furnace before working on low‑voltage wiring.
- Check 3–5A low‑voltage fuse: Locate the automotive‑style fuse on the York control board. If blown, inspect for shorts before replacing with the same rating.
- Inspect thermostat cable: Look for crushed, chewed, or bare thermostat wires between the air handler and thermostat. Repair or replace damaged cable.
- Verify thermostat wiring: Compare connections at the thermostat and control board to the York wiring diagram (R, C, Y, G, O/B, etc.). Correct any miswiring.
- Test thermostat: Temporarily jumper R to Y and G at the control board (with power on) to see if the system starts. If it does, the thermostat may be faulty and should be replaced.
- Replace fuse and retest: After correcting wiring issues, install a new fuse and restore power.
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Repair Difficulty
Medium
3/5
Required Part
Control Board Low-Voltage Fuse
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