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York Error Code AF: Low Flame Current

⚠️ 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

  1. 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.
  2. 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.
  3. 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.
  4. 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.
Type: digital display

What Does York Error Code 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.

Common Causes of York Code AF

  • Dirty or improperly positioned flame sensor
  • Weak gas pressure or a problem with the gas valve
  • Poor electrical connection to the flame sensor or control board
  • Faulty flame sensor
  • Cracked heat exchanger (can dilute the flame)
  • Control board malfunction

Applicable York Models

AHE⚡LX Series⚡Packaged⚡TM8Y⚡TM9T⚡TM9V⚡YCS⚡YXT⚡YXV⚡YZB⚡YZT⚡YZV⚡
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Need a Pro to Fix York Code AF?

This error requires immediate attention from a licensed HVAC technician. Do not attempt repair yourself.

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Replacement Parts for York HVAC System Code AF

Flame Sensor OEM: 024-27675-000
Gas Valve
Ignition Control Board