York Error Code AF: Low Flame Current
Warning: This error indicates a problem with the furnace's flame, which could lead to a dangerous buildup of unburned gas. Shut down the furnace immediately and call for professional service.
How to Fix York Code AF
- Step 1: Turn off the furnace. Locate the furnace's power switch (usually on the side of the unit) and switch it to the 'off' position.
- Step 2: Check the gas supply. Ensure that the gas supply valve to the furnace is fully open. It's typically a yellow handle running parallel to the gas pipe when open.
- Step 3: Reset the furnace. Wait at least five minutes, then turn the power switch back on. If the error reappears immediately, proceed to the next step.
- Step 4: Call a qualified HVAC technician. Due to the potential safety hazards associated with gas furnaces, it's best to have a professional diagnose and repair the issue.
How to Reset York Code AF
- Turn off the furnace power switch, usually located on or near the unit.
- Turn off the circuit breaker for the furnace. Wait 30 seconds.
- Restore power at the breaker and flip the furnace switch back on.
- Set the thermostat to call for heat. If the error code returns after 2-3 ignition attempts, the fault requires repair.
What does AF mean?
The 'AF' error code on your York furnace indicates a low flame current. This means the furnace's control board isn't detecting a strong enough electrical signal from the flame sensor. The flame sensor is a safety device that proves the burners have lit. If the sensor doesn't detect a proper flame, the furnace should shut off the gas valve to prevent a dangerous accumulation of unburned gas inside the unit. This error can occur intermittently or cause a complete lockout of the furnace, preventing it from heating your home. Because it relates to gas combustion, it's important to address this issue promptly and safely.
Affected Models
Replacement Parts
| Part | OEM Number | Est. Cost |
|---|---|---|
| Flame Sensor | 024-27675-000 | — |
| Gas Valve | — | — |
| Ignition Control Board | — | — |
Related Codes on Same Models
| Code | Description | Severity |
|---|---|---|
| R1 | Flame Without Call | Critical |
| R2 | Pressure Switch Stuck Closed | Warning |
| R3 | Pressure Switch Stuck Open | Warning |
| R4 | High Limit Switch Open | Warning |
| R5 | Rollout Switch Open | Critical |
| R6 | Gas Valve Failure | Critical |
| R7 | Ignition Lockout | Critical |
| R9 | Reversed Polarity | Critical |
| A4 | Improper Thermostat Wiring | Warning |