GUC/GUX - Flashing Code 1

Amana Gas Furnace; GUC/GUX

Re: Flashing Code 1

• If a flame was not sensed during the first 7 seconds after the gas valve was energized, the control turns off the gas.
• The control will make 3 tries before it determines that it cannot establish measureable combustion and enters a lockout state.
• If flame is established and lost after 10 seconds, the control will recycle this series of 3 tries four more times before locking out.

Light: The diagnostic light will indicate this condition with one short on flash followed by a longer off.

Reset: The control can be reset and brought out of lockout mode by turning the thermostat off and then back on.

CHECKOUT:

1. Check Glow Plug

• Look for any visual cracks.
• Use a meter to test resistance of glow plug.
  • No Resistance = Bad Glow Plug
• Check for 120V power to the Glow Plug during an ignition sequence.
  • No Power = Bad Ignition Control
  • Power + Not Glowing = Bad Glow Plug

2. Check Ignition

• Visually inspect the burners during ignition.
  • Burners should light with little or no delay from the glow plug to the flame sensor.
  • Make sure the flame sensor comes in good contact with the flame.
    • Burners ignite properly → Step 4.  Check Flame Sensor
    • Any Delay or Burners Not Igniting = Clogged Burners or Bad Gas Valve → Step 3.  Check Gas Valve
  • The glow plug should de-energize once flame is established.
    • Glow Plug Does Not De-Energize = Bad Control Board

3. Check Gas Valve

• Turn off power to the furnace and close the gas safety shut-off valve.
• Hook-up a gas pressure gauge to the inlet test port of the gas valve.
• Open the gas safety shut-off and check gas pressure.
  • Should be minimum of 5" w.c. for Nat. gas and 11" w.c. for propane.
    • No Pressure = Gas Shut-Off ⇒ Check the Meter
    • Low Pressure = Bad Meter or Regulator
• Re-apply power to the furnace and activate a call for heat.
• Check for 24VAC between the two gas valve feed wires at the time of ignition.
  • No Power = Bad Ignition Control or Bad Wires
• Make sure the inlet gas pressure stays above minimum when the gas valve energizes.
  • Pressure Drops Below Minimum = Bad Meter or Regulator
• Turn off power to the furnace and close the gas safety shut-off.
• Move the gas pressure gauge to the manifold (leaving) test port on the gas valve.
  • Be sure to put the plug back in the inlet test port before proceeding!
• Open the gas safety shut-off valve and re-apply furnace power.
• Activate a call for heat and monitor the manifold gas pressure during an ignition attempt. (3-3.5" w.c. for Nat. Gas, 9-11" w.c. for LP)
  • No Pressure = Bad Gas Valve
  • Good Pressure + No Ignition = Clogged Burners ⇒ Remove burners and clean spreaders

4. Check Flame Sensor

• DO NOT clean the flame sensor before checking!
• On the multi-meter:
  • Switch the test leads to "COM" and "mA".
  • Set the meter on DC 200ù.
  • Disconnect the wire from the flame sensor.
  • Place one meter lead on the flame sensor terminal and the other on the flame sensor wire.
  • Check the reading when the burners ignite.
    • Minimum acceptable reading = 1 MicroAmp
      • Low Reading = Dirty Flame Sensor ⇒ Clean Flame Sensor & Re-check
      • Normal Reading (2 to 6 mA) but still shuts-off = Bad Ignition Control
  • MOVE SENSOR LEADS BACK TO "COM" and "V" BEFORE PROCEEDING!