White Rodgers PS9, FL9S Furnace Cleaning Section, Troubleshooting, Furnace Control Diagnostics

127237-UUM-A-0605

A momentary loss of gas supply, flame blowout, or a faulty flame probe circuit will result in a disruption in the flame and be sensed within 1 sec- ond. The gas valve will de-energize and the control will begin a recycle operation. A normal ignition sequence will begin after a 15 second inter- purge. If during the five recycles the gas supply does not return, or the fault condition is not corrected the ignition control will lockout for one hour.

During burner operation, a momentary loss of power for 50 milliseconds or longer will de-energize the gas valve. When the power is restored, the gas valve will remain de-energized and the ignition sequence will immediately restart.

Hot Surface Ignition System

HOT SURFACE IGNITION SYSTEM

Do not attempt to light this furnace by hand (with a match or any other means). There may be a potential shock hazard from the components of the hot surface ignition system. The furnace can only be lit automatically by its hot surface ignition system.

10.Restore electrical power and gas supply to the furnace.

11.Check furnace operation.

Cleaning the Secondary Heat Exchanger

1.Follow steps 1 - 7 under cleaning the Heat Exchanger.

2.Remove the vent piping from the vent blower housing. Disconnect the drain lines from the vent blower housing and from the conden- sate drain pan. Remove the vent blower housing blower and the condensate pan.

3.Using a stiff wire brush, remove the loose scale or soot from each tube.

4.Vacuum the secondary heat exchanger.

5.Finish the cleaning procedure by following steps 9 - 11 under cleaning the Heat Exchanger.

Cleaning the Vent / Air Intake System

Should it be necessary to service the vent / air intake system, the man- ufacturer recommends this service be conducted by a qualified service agency.

The operation of this appliance requires the reassembly and resealing of the vent / air intake system as specified in the “Combustion Air and Vent System” located in the Installation Manual.

FURNACE CLEANING SECTION

NOTE: The cleaning operations listed below must be performed only by a qualified service agency.

Label all wires prior to disconnection when servicing controls. Wiring errors can cause improper and danger- ous operation. Verify proper operation after servicing.

Burner Removal/Cleaning

The main burners should be checked periodically for dirt accumulation. If cleaning is required, follow this procedure:

1.Turn off the electrical power to the unit.

2.Turn off the gas supply at the external manual shut-off valve and loosen the ground union joint.

3.Remove the upper access panel and remove the burner box cover.

4.Disconnect wires from flame sensor, rollout switch and HSI igniter. Remove igniter carefully, as it is easily broken.

5.Remove the screws that hold the burner box assembly to the vest panel and remove the assembly.

6.Remove burners from the burner assembly.

7.Burners may be cleaned by rinsing in hot water.

8.Reassemble the burners in the reverse order.

Cleaning the Heat Exchanger

1.Turn off the electrical power to the unit.

2.Turn off the gas supply at the external manual shut-off valve and loosen the ground union joint.

3.Remove the upper access panel and remove the burner box cover.

4.Disconnect wires from flame sensor, rollout switch and HSI igniter. Remove igniter carefully, as it is easily broken.

5.Remove the screws that hold the burner box assembly to the vest panel and remove the assembly.

6.Remove the vent pipe assembly, vent blower and condensate pan.

7.The heat exchanger is now exposed.

8.With a long flexible wire brush, clean inside each tube at both the top and bottom. The brush must pass around the rear heat exchanger tubes. Then vacuum loose the scale and dirt from each tube.

9.Replace all components in reverse order. Reconnect all wiring.

TROUBLESHOOTING

The following visual checks should be made before troubleshooting:

1.Check to see that the power to the furnace and the ignition control module is ON.

2.The manual shut-off valves in the gas line to the furnace must be open.

3.Make sure all wiring connections are secure.

4.Review the sequence of operation. Start the system by setting the thermostat above the room temperature. Observe the system’s response. Then use the troubleshooting section in this manual to check the system’s operation.

Never bypass pressure switch to allow furnace opera- tion. To do so will allow furnace to operate under poten- tially hazardous conditions.

Do not try to repair controls. Replace defective controls with UPG Source 1 Parts.

Never adjust pressure switch to allow furnace operation.

FURNACE CONTROL DIAGNOSTICS

The furnace has built-in, self-diagnostic capability. If a system problem occurs, a blinking LED shows a fault code. The LED can flash red, green or amber to indicate various conditions. It is located behind a clear view port in the blower compartment door.

The control continuously monitors its own operation and the operation of the system. If a failure occurs, the LED will indicate the failure code. If the failure is internal to the control, the light will stay on continuously. In this case, the entire control should be replaced, as the control is not field repairable.

Flash sequence codes 1 through 11 are as follows: LED will turn “on” for 1/4 second and “off” for 1/4 second. This pattern will be repeated the number of times equal to the code. For example, six “on” flashes equals a number 6 fault code. All flash code sequences are broken by a 2 sec- ond “off” period.

SLOW GREEN FLASH: Normal operation.

SLOW AMBER FLASH: Normal operation with call for heat.

RAPID RED FLASH: Twinning error, incorrect 24V phasing. Check twinning wiring.

RAPID AMBER FLASH: Flame sense current is below 1.5 microamps. Check and clean flame sensor. Check for proper gas flow.

6 Unitary Products Group