York P4UCB30N12206 - Troubleshooting

Turn thermostat
(controller) to
call for heat
Power at transformer
(25 vac nominal)?
Check line voltage power, low voltage transformer
thermostat (controller) and wiring
Venter begins
to operate
System runs until
call for heat ends?
Call for heat ends
System shuts off?
Troubleshooting ends
Venter Okay?
Place jumper
on relay 3R
between "1" & "3"
Venter Okay?
Repeat procedure until troublefree operation is obtained.
YES
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
Check for proper thermostat (controller) operation.
Remove MV lead at 50E47. If valve closes, replace
50E47. If not, replace gas valve
Check continuity of sensor wire and ground wire.
Note: If ground is poor or erratic, shutdown may
occur occasionally even though operation
is normal at the time of checkout.
If checks are Okay, replace 50E47 module.
Replace
venter
NO
NO
YES
Hot surface
igniter begins
to glow?
Main burner lights?
NOTE: Before troubleshooting, familiarize yourself
with the startup and checkout procedures.
Check for 25vac on 50E47 acrosss MV terminals. If no
voltage, replace 50E47.
Check electrical connections between 50E47 & gas valve.
If Okay, replace gas valve.
Place jumper on
between "C" & "NC"
pressure switch 1LP
Check hoses connected to pressure switch 1LP.
Check electrical connections between pressure
switch and plug connections.
If checks are Okay, replace pressure switch 1LP.
Check for looseness of pressure tap in burner box.
and continuity of the limit switch.
Check for cracks in hot surface igniter (replace if required)
If checks are Okay, replace pressure switch 2LP, 3LP or 4LP.
Check electrical continuity of flusible link (replace if open)
no check for loose hoses or loose pressure tap on burner box.
Check that pressure switches 2LP, 3LP & 4LP are closed. If
WHITE-RODGERS 50E47 SYSTEM TROUBLESHOOTING TABLE
650.64-N4
Unitary Products Group 15