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Reset heater, observe
heating cycle. Does
switch open?
Y
Does switch open prior
to 350°F?
DO NOT OPERATE
HEATER
System over heating,
immediately contact
technical support.
N
Locate harness
connection.
(see photo at right)
Y
Is there continuity
Through GREY
Lead wires of heater side
harness?
(see photo at right)
N
Replace vent
safety switch
(see “Vent Safety
Switch
Replacement
Procedure”)
Call technical
support.
Y
N
Depress reset
button on high
limit switch. Is
there continuity
across high limit
switch?
(see photo below)
Does heater
function?
N
Y
Is temp over 350°F?
Y
N
Sequence of operation:
For Hot Surface Ignition models, with the thermostat calling for heat, prior to energizing blower, the ignition module checks the
vent safety switch for normal switch position of normally closed. If the vent safety switch contacts are open, (not in normal
position), the ignition module waits indefinitely for contact to close, The vent safety switch must be manually reset to close the
switch contacts.
F
or Direct Spark Ignition models, error code 26 will display indicating an open circuit for the vent safety switch. Determine if
temperature has reached 350°F before resetting switch and restoring operation. If evidence of extreme temperature is present,
call technical support.
System OK
N
Y
Replace vent safety
switch
(see “Vent Safety
Switch Replacement
Procedure”)
Heater side
h
arness
Control side
h
arness
WARNING
120 volt potential exposure. Use caution
m
aking voltage checks to avoid personal injury.
Reset button
71
WARNING
Make sure exhaust collector compartment is not
overheating (350°F) before resetting vent safety
switch. If there is evidence the collector compartment
is overheating, CALL TECHNICAL SUPPORT.
71