White Rodgers 50A55-438 System Lockout And Diagnostic Features, System Lockout Features

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, and, if flame is sensed, the inducer blower is energized. The diagnostic indica- tor light will flash or glow continuously 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, 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 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.

DIAGNOSTIC FEATURES

The 50A55 control continuously monitors its own operation 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)
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/im-
	proper ground
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.

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