White Rodgers 50A66-743 Manual De Usuario

White-Rodgers is a business 
of Emerson Electric Co.

The Emerson logo is a  
trademark and service mark 
of Emerson Electric Co.

Normal operation

No fault

Normal operation with 
call for heat

Normal operation

Open limit switch

Verify continuity through rollout switch circuit

Pressure switch stuck 
closed/open

Pressure switch stuck closed. Check switch function, verify 
inducer is turning off.
Pressure switch stuck open. Check pressure switch function 
and tubing. Verify inducer is turning on and pulling sufficient 
vacuum to engage switch.

External lockout 
(retries)

Failure to sense flame is often caused by carbon deposits on 
the flame sensor, a disconnected or shorted flame sensor 
lead or a poorly grounded furnace. Carbon deposits can be 
cleaned with emery cloth. Verify sensor is not contacting the 
burner and is located in a good position to sense flame.
Ignitor must be positioned to light the gas immediately when 
the valve opens. If the ignitor has been replaced, verify hot 
spot position has not changed.
Check sensor lead for shorting and verify furnace is          
grounded properly.

Flame sensed with gas 
valve de-energized

Verify the gas is operating and shutting down properly. Flame 
in burner assembly should extinguish promptly at the end of 
the cycle. Check orifices and gas pressure. 

Open rollout switch

Verify continuity through rollout switch circuit. 

Module – internal fault 
condition

Module contacts for gas valve not operating or processor 
fault. Reset control, if condition persists, replace module. 

Low flame sense 
current

Low flame sense current is often caused by carbon deposits 
on the flame sensor, a poorly grounded furnace or a mis-
aligned flame sense probe. Carbon deposits can be cleaned 
with emery cloth.
Check or improve furnace and module ground. Verify sensor 
is located in or very near flame as specified by the appliance 
manufacturer.

Grounding or 
reversed polarity

Verify the control and furnace are properly grounded. Check 
and reverse polarity (primary) if incorrect.

Module ignitor 
contact failure

 Fault code indicates the module ignitor contacts are not 
functioning properly. Replace module.