50A52 Flow Chart 2 - American Standard *UD Series Operation Manual

50A52 Flow Chart 2

Inducer Draft Motor
and Pressure
Switch Check
Call for Heat
Thermostat Contact
R and W Close
2A
YES
Is Induced Draft
Motor Energized?
NO
Check 24 Volt
B/C to W
YES
YES
Is Limit or
Roll Out Fuse Open?
1
NO
YES
Pressure Switch
NO Contacts
Closed/Welded?
NO
Pressure Switch
NC Contacts Closed?
2
YES
24 VAC Present
at PCOM and TR
Terminals?
YES
120 VAC Present
at Inducer Hot and
IND Neutral
Terminals?
YES
Check Induced Draft
Motor Wiring , if
Okay Replace Motor
NO
Check T-Stat,
Low Voltage
Wiring & 120VAC
Replace and
Check Operation
Replace
Pressure
Switch
NO
Replace
Switch
NO
Check Wiring,
If Okay Replace
Ignition Control
NO
Replace
Control
1 Does Not Apply to E93, E1 or E2 controls, inducer is energized if limit or roll out opens.
2 E93, E1 or E2 controls do not require normally closed pressure switch input.
2B
YES
Did
Pressure Switch
Normally Open
Contacts Close?
NO
Jumper PCOM
to PO After Call
for Heat
NO
Does HSI Glow?
YES
YES
Is Pressure Switch
Static Greater Than
Switch Specs?
NO
Remove Vent from
Furnace Connector
Is
YES
Pressure Switch
Static Greater Than
Switch Specs
Now?
NO
Check for Leaks
in Inducer Assembly,
Corroded Inducer
Wheel, Tight
Bearings.
Replace Motor.
62
Chart 3
Chart 3
Check Hose
Connections for
Leaks or Cracks.
Replace Switch.
Correct Blocked
or Restricted
Vent System.