York GY8S Series User's Information, Maintenance And Service Manual

Contents

York GY8S Series User's Information, Maintenance And Service Manual Manual pdf 7 page image

268893-UUM-A-0407Unitary Products Group 7Hot Surface Ignition SystemTROUBLESHOOTINGThe following visual checks should be made before troubleshooting:1. Check to see that the power to the furnace and the ignition controlmodule is ON.2. The manual shut-off valves in the gas line to the furnace must beopen.3. Make sure all wiring connections are secure.4. Review the sequence of operation. Start the system by setting thethermostat above the room temperature. Observe the system’sresponse. Then use the troubleshooting section in this manual tocheck the system’s operation.FURNACE CONTROL DIAGNOSTICSThe furnace has built-in, self-diagnostic capability. If a system problemoccurs, a blinking LED shows a fault code. The LED can flash red,green or amber to indicate various conditions. It is located behind aclear view port in the blower compartment door.The control continuously monitors its own operation and the operationof the system. If a failure occurs, the LED will indicate the failure code. Ifthe failure is internal to the control, the light will stay on continuously. Inthis case, the entire control should be replaced, as the control is notfield 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 thenumber of times equal to the code. For example, six “on” flashes equalsa 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. Checktwinning wiring.RAPID AMBER FLASH: Flame sense current is below 1.5 microamps.Check and clean flame sensor. Check for proper gas flow. Verify thatcurrent is greater than 1.5 microamps at flame current test pad.4 AMBER FLASHES: The control board is recieving a “Y” signal fromthe thermostat without a “G” signal, indicating improper thermostat wir-ing.1 RED FLASH: This indicates that flame was sensed when there wasnot a call for heat. With this fault code the control will turn on both theinducer motor and supply air blower. A gas valve that leaks through oris slow closing would typically cause this fault.2 RED FLASHES: This indicates that the normally open pressureswitch contacts are stuck in the closed position. The control confirmsthese contacts are open at the beginning of each heat cycle. This wouldindicate a faulty pressure switch or miswiring.3 RED FLASHES: This indicates the normally open pressure switchcontact did not close after the inducer was energized. This could becaused by a number of problems: faulty inducer, blocked vent pipe, bro-ken pressure switch hose or faulty pressure switch.4 RED FLASHES: This indicates that a primary or auxiliary limit switchhas opened its normally closed contacts. With this fault code the controlwill operate the supply air blower and inducer. This condition may becaused by: dirty filter, improperly sized duct system, incorrect blowerspeed setting, incorrect firing rate or faulty blower motor.5 RED FLASHES: This fault is indicated if the normally closed contactsin the rollout switch opens. The rollout control is manually reset. If it hasopened, check for proper combustion air, proper inducer operation, andprimary heat exchanger failure or burner problem. Be sure to reset theswitch and cycle power (24 VAC) to the control after correcting the fail-ure condition.6 RED FLASHES: This indicates that after the unit was operating, thepressure switch opened 4 times during the call for heat. If the mainblower is in a “Delay on” mode, it will complete it, and any subsequentdelay off period. The furnace will lock out for one hour and then restart.7 RED FLASHES: This fault code indicates that the flame could not beestablished. This no-light condition occurred 3 times (2 retries) duringthe call for heat before locking out. Low gas pressure, faulty gas valve,dirty or faulty flame sensor, faulty hot surface ignitor or burner problemmay cause this. The furnace will lock out for one hour and then restart.8 RED FLASHES: This fault is indicated if the flame is lost 5 times (4recycles) during the heating cycle. This could be caused by low gaspressure, dirty or faulty flame sensor or faulty gas valve. The furnacewill lock out for one hour and then restart.9 RED FLASHES: Indicates reversed line voltage polarity or groundingproblem. Both heating and cooling operations will be affected. Checkpolarity at furnace and branch. Check furnace grounding. Check thatflame probe is not shorted to chassis.10 RED FLASHES: Gas flow with no call for heat. Check gas valve andgas valve wiring.11 RED FLASHES: This indicates that a primary or auxiliary limit switchhas opened its normally-closed contacts and has remained open formore than five minutes. This condition is usually caused by a failedblower motor or blower wheel. Cycle power (24 VAC) to the control toreset the hard lockout condition after correcting the failure condition.12 RED FLASHES: This code indicates an open igniter circuit, whichcould be caused by a disconnected or loose wire or by a cracked or bro-ken igniter.STEADY ON RED: Control failure. Replace control board.60-MINUTE AUTOMATIC RESET FROM LOCKOUT: This controlincludes a “watchdog” type circuit that will reset from a lockout conditionafter 60 minutes. Operational faults 6,7,8 will be reset. This providesprotection to an unoccupied structure if a temporary condition existscausing a furnace malfunction. An example would be a low incominggas supply pressure preventing unit operation. When the gas pressureis restored, at some point the “watchdog” would restart the unit and pro-vide heat for the house.NOTE: If a flame is detected the control flashes the LED for 1/8 of asecond and then enters a flame stabilization period.HOT SURFACE IGNITION SYSTEMDo not attempt to light this furnace by hand (with amatch or any other means). There may be a potentialshock hazard from the components of the hot surfaceignition system. The furnace can only be lit automaticallyby its hot surface ignition system.Never bypass any safety control 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 controlswith UPG Source 1 Parts.Never adjust pressure switch to allow furnace operation.IGNITION CONTROLNormal flame sense current is approximately3.7 microamps DC (μa)Low flame signal warning starts at 1.5 microamps.Low flame signal control lockout point is0.1 microamps DC (μa)