Garland MCO-GD-10M Service Manual

Contents

Garland MCO-GD-10M Service Manual Manual pdf 13 page image

13The safety lockout timer circuit starts timing the moment the trial for pilot ignition starts. When the timing period runsout, the trial for ignition ends, and the control module goes into lockout. Before another attempt to start can be made,the S86 must be reset. Reset by adjusting the thermostat or controller or to its "OFF" position. An alternate method isto shut the system power "OFF". If normal ignition does not occur, use the trouble shooting table to determine theproblem.SERVICEPRELIMINARY CHECKThe following visual checks should be made before trouble shooting and after installation or maintenance.1. Check power to appliance and S86.2. Manual shutoff cocks in gas line to appliance must be open.3. Make certain all wiring connections are clean and tight.4. First de-energize the system and wait at least one (1) minute. This resets the module allowing a return to startcondition. Then energize the system.5. Review the S86 system normal sequence of operation.SYSTEM TROUBLE SHOOTINGStart the system by setting the thermostat or controller above required temperature. Observe system response.Establish type of malfunction or deviation from normal operation. Use the S86 Intermittent Pilot System TroubleShooting Table to check for normal system operation.Use table by following instruction questions in box. If the condition is true or okay (answer yes), go down to next boxunderneath. If the condition is not true or not okay (answer no), go right to the next box alongside. Continue checking2222 SPARK GENERATOR POWEREDFirst valve (pilot) operator opens3333 PILOT BURNER OPERATIONPilot burner lights.Module senses flamecurrent.OR Pilot burner does not light.After 90 seconda systemlocks out; must be manuallyreset.a Shutoff/lockout timing is stamped on module.4444 FLAME CURRENT SENSED• Spark generator off.• Second valve operation (main) opens.5555 MAIN BURNER OPERATIONModule monitors pilot flame current.6666 THERMOSTAT (CONTROLLER) SATISFIEDValves close, pilot and main burners are off.1111 THERMOSTAT (CONTROLLER) CALLSFOR HEATPOWER INTERRUPTIONSystem shuts off, restartswhen power is restored.PILOT FLAME FAILUREMain valve closed.Module starts trial for ignition.STARTSTAGE 1TRIAL FORIGNITIONSTAGE 2MAIN BURNEROPERATIONEND