White Rodgers 50A55-743 Benutzerhandbuch

6

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.

The 50A55-743 control continuously monitors its own op-
eration and the operation of the system. If a failure occurs, 
the LED will indicate a failure code as shown below. 

failure is internal to the control, the light will stay off. 
In this case, the entire control should be replaced, as 
the control is not field-repairable.
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).
1 flash, then pause 

System lockout

2 flashes, then pause  Pressure switch stuck closed
3 flashes, then pause  Pressure switch stuck open
4 flashes, then pause  Open limit switch
5 flashes, then pause  Flame has been sensed when 

no flame should be present (no 
call for heat)

6 flashes, then pause  Open rollout switch
7 flashes, then pause  Low flame sense signal
Continuous flashing 

115 Volt AC power reversed

OFF 

  Control 

failure

ON 

  Normal 

operation

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.

If the control has six screw terminals, one of which is 
designated 

TWIN, the control is equipped with a single 

wire twinning interface. If twinning is used, either control 
will process a call for heat, cool or fan as described above. 
However, after the heat-, cool-, or fan-on delay time ex-
pires, both units will energize the circulator blowers at the 
same time. Likewise, after the heat-, cool-, or fan-off delay 
time expires, both units will de-energize the circulator 
blowers at the same time. This allows for proper air flow 
to be obtained. To assure proper control operation, both 
controls must share a common transformer ground (TR).
To enable twinning, do the following.
1.  Power supplied to both furnaces must be from the 

same phase of the incoming 120 VAC power.

2.  Connect the 

TWIN screw terminals on the 50A55-743 

of the furnaces to be twinned to each other using a 
single wire (14-22 AWG.).

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 indicator light will flash or glow continuously 
to indicate system status.