Form I-UDA, P/N 195673 Rev 13, Page 35
10..11. Door Switch
- UDAS
only
If it is determined that the door switch needs replacing, use only a factory-
authorized replacement part that is designed for the heater.
For approximate switch location, see
FIGURE 18
, page 30.
10..1 Transformer
See
FIGURE 18
, page 30, for location. Use a voltmeter to verify that
there are 24 volts output from the transformer. If the transformer is not
functioning, it must be replaced. Use a replacement transformer identi
-
cal to the factory-installed model.
10.3 Troubleshooting
10..10 Flame Rollout
Switch - Sizes 30-15
only
10..14 Vent or Vent/
Combustion Air
System
For location, see
FIGURE 18, page 30.
The cause of a flame rollout switch activating must be determined. Activation of the
manually reset flame rollout switch could be caused by one or more of the following:
• Restricted combustion air inlet or exhaust outlet
in combination with a defective pressure switch
• Electrical power interruption during operation
• Unit being operated with a line voltage discon
-
nect (a 24-volt thermostat is required)
If a flame rollout switch trips, inspect the burner/control compartment for signs of exces
-
sive heat and burned wiring.
If the compartment appears normal,
reset by depressing the red button on the
switch. 15 to 20 minutes are required for the switch to cool sufficiently for reset
-
ting. A distinct click will be felt when the switch resets. Operate the furnace. If the
flame rollout switch trips again, determine and correct the cause before resetting
the switch.
If there is damage to the control compartment,
repairs must be made before
resetting the switch.
If it is determined that the flame rollout switch needs replacing, use only the factory-
authorized replacement part that is designed for that size of heater.
The disconnect switch is located in the sealed electrical box inside the control compart
-
ment with the toggle on the rear of the heater.
10..13 Disconnect
Switch - UDAS
only
• Restricted or plugged heat
exchanger
• Too much building exhaust
• Manifold gas pressure too
high
If it is determined that the disconnect switch needs replacing, use only the fac
-
tory-authorized replacement part that is designed for the heater. Always replace
electrical box cover.
Check the complete system at least once a year. Inspection should include all joints,
seams, concentric adapter box (UDAS), inlet air guard or inlet air cap (UDAS), and the
vent terminal cap. Clean openings. Replace any defective parts.
Check the Lights on
the DSI Integrated
Control Module
(Circuit Board)
The integrated circuit board monitors the operation of the heater and includes two
LED signal lights that indicate normal operation and various abnormal conditions. If
the heater fails to operate properly, check this signal to determine the cause and/or
to eliminate certain causes. LED is visible through viewport on Model UDAS. Remove
access panel on Model UDAP. See operating sequence in Paragraph 9.
Do not attempt to repair the DSI integrated control module (circuit board); the only field
replaceable component is the fuse.
