PG - Burners Won't Ignite

Goodman Package Units: PG

Re: Burners Won't Ignite

Important! These units have a "positive pressure" burner compartment. The burner compartment cover must be in place when the main burners ignite.

These package gas/electric units use a Honeywell Smart Valve for ignition.

• Sequence Of Operation
• On a call for heat, the fan timer board starts the inducer fan motor and sends 24V through the end switch and roll-out switch to the Smart Valve.
• When the Smart Valve receives a demand for heat it powers the 24V glow plug and opens the pilot valve.
• When a pilot flame is sensed, the Smart Valve opens the main valve to allow gas flow to the burners.

CHECKOUT:

1. Check Ignition Sequence

• Initiate a call for heat.
• Check for 24VAC between "R" and "C".
  • No Power ⇒ Check Inlet Power, Low Voltage Fuse and Limit Switches
• Check for 24VAC between "W" and "C".
  • No Power = No Call from the Thermostat
• Ensure that the inducer motor starts properly.
  • Motor Doesn't Start → Step 2. Check Inducer
• Check for 24VAC between terminal 1 & 3 "Wht" and "Blu" wire on the Smart Valve.
  • No Power = Open End Switch or Tripped Roll-Out
  • Power → Step 3. Check Glow Plug/Pilot Flame

2. Check Inducer Motor

• Check for 230VAC power between "Ind Dft" (Red) or (Blk) on the fan timer board and (Brn) (connected to L1 of the contactor).
  • No Power = Bad Control Board
  • Power + No Inducer = Bad Inducer Motor

3. Check Glow Plug/Pilot Flame

• Check to see if the glow plug (mounted in the pilot assembly) glows.
  • No Glow ⇒ Check for 24VAC on the two Blue wires at the Smart Valve (while plugged-in).
    • No Power = Bad Smart Valve
    • Power + No Glow = Bad Glow Plug
• Check to see if the pilot lights.
  • Pilot Doesn't Light ⇒ Disconnect the aluminum pilot line from the gas valve and see if gas is coming out.
    • No Pilot Gas = Bad Smart Valve
    • Pilot Gas Present → Step 5. Check Pilot Orifice
• Observe the pilot flame to ensure that it comes into steady contact with the flame sensor.
  • Steady Contact + No Main Flame → Step 6: Check Flame Sensor
  • No or Low Pilot → Step 4. Check Gas Pressure

4. Check Gas Pressure

• Disconnect line voltage power from the unit.
• Shut the gas safety shut-off valve to the unit.
• Hook-up a gas pressure gauge to the inlet gas pressure port.
• Open the gas safety shut-off valve & monitor inlet gas pressure.
  • No or Very Low Pressure = Gas Supply Issue
• Re-apply power to the unit.
• Energize a call for heat.
• Monitor inlet pressure while the glow plug energizes.
  • Inlet Pressure Drops Below Normal = Gas Supply Issue
  • Inlet Pressure OK → Step 5. Check Pilot Orifice

5. Check Pilot Orifice

• Disconnect the aluminum pilot tubing from the gas valve.
• Energize a call for heat.
• Ensure that gas comes out of the pilot gas port.
  • No Pilot Gas = Bad Smart Valve
  • Pilot Gas Present ⇒ Blow through the pilot tubing to ensure the pilot orifice is clear.
    • Pilot Orifice Clear ⇒ Increase Pilot Gas Pressure

6. Check Flame Sensor

• Disconnect the pilot tubing from the gas valve (if not already disconnected).
• Remove the two screws that mount the pilot assembly to the burner manifold.
• Carefully remove the pilot assembly along with the pilot tubing.
• Clean the flame sensor. BE CAREFUL NOT TO BREAK THE GLOW PLUG!
• Re-install the pilot assembly and re-connect the pilot tubing.
• Energize a call for heat.
• Ensure that the pilot lights and the main burners ignite.
  • Pilot + No Main Gas = Bad Smart Valve
  • Pilot + Main Gas + No Main Flame = Clogged Burners ⇒ Remove burners and clean burner wings.