White Rodgers 21D83M-843 System Lockout And Diagnostic Features, Cool Mode, Manual Fan On Mode

OPERATION

If flame is detected, then lost, the 50A66-843 control will repeat the initial ignition sequence for a total of three "recycles". After three unsuccessful "recycle" attempts, the control will go into system lockout.

If flame is established for more than 10 seconds after igni- tion, the 50A66-843 controller will clear the ignition attempt (or retry) counter. If flame is lost after 10 seconds, it will restart the ignition sequence. This can occur a maximum of four times before system lockout.

A momentary loss of gas supply, flame blowout, or a shorted or open condition in the flame probe circuit will be sensed within 2 seconds. The gas valve will de-energize and the control will restart the ignition sequence.Recycles will begin and the burner will operate normally if the gas supply returns, or the fault condition is corrected, before the last ignition attempt. Otherwise, the control will go into system lockout.

If the control has gone into system lockout, it may be pos- sible to reset the control by a momentary power interrup- tion of ten seconds or longer.Refer to PRECAUTIONARY,

SYSTEM LOCKOUT, AND DIAGNOSTIC FEATURES.

COOL MODE

In a typical system, a call for cool is initiated by closing the thermostat contacts. This energizes the 50A66-843 control's cooling sequence.The compressor is energized and the delay-to-fan-on period begins. After the delay- to-fan-on periods ends, the circulator fan is energized at cool speed. The electronic air cleaner (optional) is also energized. After the thermostat is satisfied, the compres- sor is de-energized and the delay-to-fan-off period begins. After the delay-to-fan-off period ends, the circulator fan and electronic air cleaner (optional) are de-energized.

MANUAL FAN ON MODE

If the thermostat fan switch is moved to the ON position, the circulator fan (heat speed) and optional electronic air cleaner are energized. When the fan switch is returned to the AUTO position, the circulator fan and electronic air cleaner (optional) are de-energized.

SYSTEM LOCKOUT AND DIAGNOSTIC FEATURES

SYSTEM LOCKOUT FEATURES

When system lockout occurs, the gas valve is de-energized. The circulator blower is energized at heat speed for some faults, and if flame is sensed, the inducer blower is en- ergized. The diagnostic indicator light will flash or glow continuously to indicate system status. (System lockout will never override the precautionary features.)

To reset the control after system lockout, do one of the following:

1.Interrupt the call for heat at the thermostat for at least onesecond,butlessthan20seconds(ifflameissensed with the gas valve de-energized, interrupting the call for heat at the thermostat will not reset the control).

2.Interrupt the 24 VAC power at the control for at least ten seconds. You may also need to reset the flame rollout sensor switch.

3.After one hour in lockout, the control will automatically reset itself.

DIAGNOSTIC FEATURES

The 50A66-843 control continuously monitors its own operation and the operation of the system. If a failure oc- curs, the DS 1 (red) and DS 2 (green) LEDs will indicate a failure code as shown on next page.

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