| Burner Blower Motor | Visually check to see if motor is running. If not, |
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| check for 120 VAC to motor at motor connector (wire |
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| #5 and #22). If voltage is not present, trace wiring |
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| back to fan switch. If voltage is present and motor is |
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| not running, check for opens, shorts, or grounds. |
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| Also, WITH POWER OFF: check for locked rotor. |
| Transformer, Burner | Primary is 120 VAC with 24 VAC secondary. If 120 |
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| VAC is not present, trace wiring back to Main Fan |
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| Centrifugal Switch. If 120 VAC is present, check for |
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| 24 VAC at secondary of transformer. If no voltage is |
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| present, replace transformer. |
| Centrifugal Switch of Burner | Check of 120 VAC at motor connector, on wire #13 |
| Blower Motor | to neutral. If voltage is not present, trace wiring back |
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| to transformer. If voltage is not present and motor is |
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| running, replace the burner blower motor. |
| Ignition Control | 24 volts should be present at 24 volt terminals. If not |
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| present, trace wiring back to centrifugal switch. |
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| When 24 VAC is supplied, the control switches 120 |
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| VAC from L1 and L2 to the hot surface ignitor. if 120 |
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| VAC is not present at L1 and L2, trace wiring |
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| back to fan switch. If 24 VAC and 120 VAC are |
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| present and 120 VAC is not across the hot surface |
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| ignitor terminals, replace the ignition control. |
| Hot Surface Ignitor | If 120 VAC is present at hot surface ignitor terminals, |
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| visually check to see that the ignitor is heating. |
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| (Ignitor may be viewed through the port glass in end |
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| of burner tube.) The ignitor should glow bright red. |
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| If the ignitor does not heat, replace the ignitor. |
| Ignition Control | After 45 seconds of hot surface ignitor |
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| ignition control will switch 24 VAC to the gas control |
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| valves. Check for 24 VAC output from ignition |
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| control, across terminals marked "valve" and "valve |
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| ground". If no voltage is present, replace ignition |
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| control. |
| Gas Control Valves | When 24 VAC is supplied to the gas control valve, |
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| the valve should open. Check for gas pressure at |
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| the manifold tap located just before the burner. If |
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| there is no pressure, check the incoming gas supply |
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| to be sure all manual valves are open and flexible |
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| gas hose is properly connected. If gas is present |
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| and coils of gas valve are energized, the gas valve is |
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| probably defective. |
Flame will not stay lit | Hot Surface Ignitor | Six seconds after the gas valve opens, ignition must |
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| occur. if flame is not detected, the ignition control |
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| will shut off and lock out. To reset the ignition |
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| control, turn off the burner switch for 45 seconds, |
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| then turn on the burner switch to retry ignition. The |
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| ignition control requires a minimum of 0.8 D.C. |
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| microamps. To check flame sensing operation, |
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| connect a digital multimeter (capable of measuring |
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| D.C. |
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| ignition control and the ground lead. |
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| NOTE: This is a current measurement and the |
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| meter must be connected in series. If these |
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| readings are not achieved, replace the hot surface |
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| ignitor. |
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| NOTE: The D.C. micro amp test must be conducted |
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| with the oven in low flame (bypass) operation. Turn |
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| the temperature control to the lowest setting. |
Impinger II | 9 |
