White Rodgers 50A55-571 Cool Mode, Manual FAN on Mode, System Lockout Diagnostic Features

gize and the control will restart the ignition sequence. A recycle 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 possible to reset the control by a momentary power interruption of one second or longer. Refer to SYSTEM LOCKOUT FEATURES.

COOL MODE

In a typical system, a call for cool is initiated by closing the thermostat contacts. This energizes the 50A55 control. The compressor and optional electronic air cleaner are energized, and the circulator fan is energized at cool speed. After the thermostat is satisfied, the compressor is de-energized and the (optional) cool mode delay-to-fan- off period begins. After the optional delay-to-fan-off period ends, the circulator fan and electronic air cleaner (op- tional) 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

DIAGNOSTIC FEATURES

The 50A55 control continuously monitors its own opera- tion and the operation of the system. The LED light on the control will flash slowly (one flash per second) if there are no failures and no call for heat. If there is a call for heat, the LED will flash quickly (one flash per half-second). If a failure occurs, the LED will indicate a failure code as shown below. 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. If the LED is continuously off, there may be no power to the control; the fuse on the control may be open; or there may be a failure in the control.

If the sensed failure is in the system (external to the control), the LED will flash in the following flash-pause sequences to indicate failure status (each flash will last approximately 0.25 seconds, and each pause will last approximately 2 seconds).

2 flashes, then pause	System lockout (no flame)/check
	line polarity
3 flashes, then pause	Pressure switch problem
4 flashes, then pause	Thermal protection device open
5 flashes, then pause	Flame sensed with gas valve off
6 flashes, then pause	115 Volt AC power reversed
7 flashes, then pause	Gas valve circuit error
8 flashes, then pause	Low flame sense signal

The LED will also flash once at power-up.

SYSTEM LOCKOUT FEATURES

When system lockout occurs, the gas valve is de-ener- gized, the circulator blower is energized at heat speed, and, if flame is sensed, the inducer blower is energized. The diagnostic indicator light will flash or glow continu- ously to indicate system status. (System lockout will never override any precautionary features.)

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

1.Interrupt the call for heat or cool at the thermostat for at least one second but less than 20 seconds (if flame is sensed with the gas valve de-energized, interrupt- ing the call for heat at the thermostat will not reset the control).

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

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

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