Emerson 50M56-7433 Manuel D’Utilisation

7

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. 

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.

The 50M56-743 control continuously monitors its own 
operation and the operation of the system. If a failure occurs, 
the LED will indicate a failure code as shown on page 8. 

the failure is internal to the control, the LED will stay off
or flash 8 times. In this case, the entire control should be
replaced, as the control is not field-repairable.
Failure codes will flash the LED 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).

The last five fault codes stored can be displayed on the 
diagnostic LED. When the control is in standby mode (no 
call for heat or cool), press the FAULT RECALL switch for 
approximately two seconds or until the diagnostic LED turns 
off. Release the switch and the LED will remain off for two 
seconds. Then the fault codes will display beginning with the 
most recent fault first with a two second pause between codes. 
After the stored fault codes have all displayed, the LED will 
remain off for two seconds and then turn on to indicate return 
to normal status. While displaying the stored fault codes, the 
control will ignore any new call for heat, cool or fan.

The stored fault codes can be erased from memory. When 
the control is in standby mode (no call for heat or cool), press 
the FAULT RECALL switch for five to ten seconds or until 
the diagnostic LED begins to rapid flash. When the switch is 
released, the LED will turn off for two seconds to indicate the 
codes are erased. After two seconds the LED will turn on to 
indicate return to normal status. If the switch is held pressed 
for over ten seconds the rapid flash will stop and the LED will 
be on to indicate return to normal status.

The 50M56-743 has only one serviceable part –an automotive 
type fuse, which protects the low voltage transformer from 
damage if the output is short-circuited. If the fuse has opened 
up, remove whatever caused the short circuit and replace the 
fuse with only a 3 Amp automotive type fuse. If the fuse does 
not correct the condition, replace the entire 50M56-743 control. 
There are no other user serviceable parts.