York Package Gas/Electric: PCG4
Re: Flashing Code 7
Code 7 = Failure to Sense Flame (3 Failed Ignition Attempts)
Qty |
Possible Causes: |
1 |
Dirty Flame Sensor |
|
Bad Glow Plug |
1 |
Clogged Burners |
1 |
No or Low Gas Pressure |
1 |
Bad Gas Valve |
|
Bad Ignition Control |
CHECKOUT:
1. Check Ignition Sequence
- Initiate a call for heat from the thermostat and monitor the ignition sequence.
- 1. The inducer motor should start with no difficulty.
- 2. The pressure switch should close within a couple seconds of the inducer starting.
- 3. The Gas Valve should open and the Sparker start sparking once the pressure switch closes.
2. Check Sparker
- Turn off power to the furnace.
- Remove the Spark Electrode from the burner compartment.
- Check to make sure the Spark Electrode is not broken or badly corroded.
- Check the Spark Wire to make sure it is not damaged.
- Spark Electrode & Wire OK ⇒ Check for 24VAC at the Gas Valve during an ignition attempt.
- 24VAC at Gas Valve + No Spark = Bad Control Board
3. Check Ignition
- Visually inspect the burners during ignition.
- The burners should light smoothly with little or no delay from the Spark Electrode to the flame sensor.
- Make sure the flame sensor comes in good contact with the flame.
4. Check Gas Valve / Pressure
- Restart a call for heat and check for 24VAC across the two wires at the Gas Valve at the point of Ignition.
- No Power = Bad Ignition Control
- Power + No Ignition ⇒ Check Gas Pressure (below)
- Check Inlet Gas Pressure
- Minimum Pressure = 5" w.c. for Nat. gas, and 10" w.c. for LP.
- Low Pressure = Gas Supply Issue
- Re-apply power to the furnace and activate a call for heat.
- Make sure the inlet gas pressure stays above minimum when the gas valve energizes.
- Pressure Drops Below Minimum = Gas Supply Issue
- Check Manifold Gas Pressure
- Normal Pressure = 3 to 3.5" w.c. for Nat. Gas, 9 to 11" w.c. for LP.
- Activate a call for heat and monitor the manifold gas pressure during an ignition attempt.
- No Gas Pressure = Bad Gas Valve
- Low Gas Pressure ⇒ Attempt to Increase Manifold Gas Pressure
- Won't Increase = Bad Gas Valve
- Normal Gas Pressure + No or Delayed Ignition = Clogged Burners ⇒ Remove burners and clean spreaders
5. Check Flame Sensor
- Check the flame sensor reading when the burners ignite.
- Normal Reading = 2 to 6 mA
- Minimum acceptable reading = 1 MicroAmp
- Low Reading = Dirty Flame Sensor ⇒ Clean the Flame Sensor & Re-check
- CAUTION! Move meter leads back to "COM" and "V" before proceeding!