LAARS U.H.E. - Service Manual - Manual (Page 36)

LAARS Heating Systems Page 36
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 page 37)
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:
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.
System OK
N
Y
Replace vent safety
switch
(see page 37)
Heater side
harness
Control side
harness
WARNING
120 volt potential exposure. Use caution
making voltage checks to avoid personal injury.
Reset button
36
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.