Amana Package Unit: PGB

Re: Flashing Code 4

Code 4 = Open Limit Circuit

There are three limits in the limit circuit:

• Primary Limit (Auto-Reset)
• Auxiliary Limit (Manual-Reset in Blower Compartment)
• Roll-Out Limit (Manual-Reset)

► If the Primary Limit trips 5 times during a single call for heat, the control will enter a Lockout and flash Code 8.

CHECKOUT:

1. Check Limit Circuit

• Limit Circuit 
• On the ignition control board, check for 24VAC between PP-5 >> OR-49 and Gnd.
• Check for 24VAC between PP-4 >> BR-21 and Gnd.
  • Power on Both = Limit Circuit Closed 
    • Limit Circuit Closed + Code 4 = Bad Control Board
    • Limit Circuit Closed + Normal Operation → Step 2. Check Blower Operation
  • Power on One Side Only = Limit Circuit Open ⇒ Check Primary limit
• Primary Limit
• At the Primary Limit, check for 24VAC between OR-49 and Gnd.
• At the Primary Limit, check for 24VAC between OR-19 and Gnd.
  • Power on Both = Primary Limit Closed ⇒ Check Auxliary Limit
  • Power on One Only = Primary Limit Open
    • Open Limit + Cool Chamber = Bad Primary Limit
• Auxiliary Limit
• At the Roll-Out Limit, check for 24VAC between OR-22 and Gnd.
  • Power Present = Auxilary Limit Closed ⇒ Check Roll-Out Limit
  • No Power = Auxiliary Limit Open ⇒ Reset Auxiliary Limit (in blower compartment) & Check Blower Operation
• Roll-Out Limit
• At the Roll-Out Limit, check for 24VAC between OR-22 and Gnd.
• At the Roll-Out Limit, check for 24VAC between BR-21 and Gnd.
  • Power on Both = Roll-Out Limit Closed 
  • Power on One Only = Roll-Out Limit Open ⇒ Manually reset the roll-out limit and check for a Bad Heat Exchanger.

2. Check Blower Operation

• Initiate a call for heat (Reset the control if necessary by cycling power.)
• Ensure that the burners fire and the blower motor starts withing 60 seconds.
  • Burners + No Blower Operation ⇒ Check for 240VAC between "M1" and "HEAT" at the ignition control board.
    • Power + No Blower = Bad Blower Motor or Capacitor
    • No Power = Bad Ignition Control Board

3. Check Temperature Rise

• Initiate a call for heat (Reset the control if necessary by cycling power.)
• Ensure that the burners fire and the blower motor starts withing 60 seconds.
• Monitor the heat exchanger temperature rise.
  • Temperature Rise > Furnace Rating → Step 4. Check Air Filter
  • Temperature Rise < Furnace Rating + Primary Limit Opens = Bad Limit

4. Check Air Filter

• Remove the air filter and re-check the temperature rise.
  • Temperature Rise Becomes Normal = Clogged or Under-Sized Air Filter
  • Temperature Rise Still > Furnace Rating → Step 5. Check Gas Pressure

5. Check Gas Pressure

• Activate a call for heat and monitor the manifold gas pressure when the gas valve opens.
  • Natural Gas = 2.5" w.c. minimum to 3.5" w.c. maximum
  • LP Gas = 9" w.c. minimum to 11" w.c. maximum
    • Pressure Below Maximum → Step 6. Check Duct Static/Blower Speed
    • Pressure Above Maximum ⇒ Lower Manifold Gas Pressure & Re-check Temperature Rise

6. Check Duct Static/Blower Speed

• Check the return static pressure (in the blower door if possible).
• Check the supply static pressure.
  • High Duct Static = Above 0.5" w.c.
    • High Return Static + Low Supply Static = Restricted Return Ductwork or Clogged Coil
    • Low Return Static + High Supply Static = Restricted Supply Ductwork
    • Normal Duct Static ⇒ Increase the blower speed and re-check the temperature rise.