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Heat & Glo • HE36CLX-S • 2183-900 Rev. H • 1/14
D. Limit Switch Circuit Operation
The limit switch circuit is ignored unless a call for heat is
present (W energized). If the limit switch circuit is open
and a call for heat is present, the control de-energizes the
gas valve and runs the circulating fan and the induced
draft motor.
When the switch re-closes or the call for heat is lost, the
control runs the induced draft motor through post-purge
and runs the circulating fan through the selected fan off
delay. The control will return to normal operation after the
blower off delay is completed.
E. Pressure Switch
If the pressure switch opens during prepurge before
the Ignition Trial period, the induced draft motor will run
through the pressure switch recognition delay (2 sec-
onds). If the pressure switch is still open the control will
re-start the pressure switch proving sequence if the call
for heat still exists.
Pressure switch opening for less than 2 seconds during
the Ignition Trial period shall not interrupt the heat cycle.
(Gas valve will de-energize while the pressure switch is
open). If the Ignition Trial is not successful, the control will
fl
ash appropriate code during the inter-purge period.
If the pressure switch opens during run mode, the pres-
sure switch will de-energize the gas valve. If
fl
ame is lost
before the end of the 2-second pressure switch recogni-
tion delay, the control will respond to the loss of
fl
ame.
If the pressure switch remains open for 2 seconds and
fl
ame remains, the control de-energizes the gas valve,
the induced draft motor runs through post-purge, and the
circulating fan runs through the selected fan off delay.
When the fan off delay is over, the circulating fan is de-
energized, and a heat cycle is initiated if the call for heat
still exists.
3. Damper Operation
With no call for Damper Transition, Damper 1 is powered
open while Damper 2 is closed.
When the thermostat calls for Damper Transition (“D”)
the damper control relay switches to close Damper 1 and
open Damper 2
When the thermostat removes the call for Damper Tran-
sition, the control relay switches to open Damper 1 and
close Damper 2.
Damper Transition has no impact on Call for Heat or Man-
ual Fan Operation.
4. Manual Fan Operation
When the thermostat calls for fan (“G”) without a call for
heat, the circulating fan is energized after an approxi-
mately 2.5 second delay. It remains energized as long as
the call for fan remains in place. If a call for heat (“W”) oc-
curs during call for fan, the circulating fan is de-energized
and a normal heating sequence will occur.
A call for fan
is ignored while in soft lockout.
5. Fault Modes
A. Flame Sensed Out of Sequence
Flame sensing only occurs when the inducer is running.
If
fl
ame is sensed longer than 20 seconds while the gas
valve is de-energized, the control shall continue running
the inducer and will turn on the circulating fan. When
fl
ame is no longer sensed, the inducer will run through
post-purge and the circulating fan will run through the se-
lected heat fan off delay time. The control will proceed to
soft lockout. The proper diagnostic code will
fl
ash.
B. Gas Valve Relay Fault
If the control senses the gas valve as energized for more
than 1 second when the control is not attempting to ener-
gize the gas valve, the control will go to soft lockout. The
control assumes either the contacts of the relay driving
the gas valve have welded shut, or the sensing circuit
has failed. The inducer is turned off to open the pressure
switch and stop gas
fl
ow by shutting off power to the gas
valve circuit, unless a
fl
ame is present. The proper diag-
nostic code will
fl
ash.
6. Lockout
A. Soft Lockout
The control shall not initiate a call for heat or call for fan
while in soft lockout. The control will respond to an open
limit if a call for heat is pending. Soft lockout shall auto-
matically reset after 1 hour and a new light off sequence
will begin if the call for heat is still in place. Soft lockout
may be manually reset by removing power from the con-
trol for more than 1 second or removing the thermostat
call for heat for more than 3 and less than 20 seconds.
B. Hardware Failure Lockout
If the control detects a fault on the control board, the prop-
er diagnostic code will
fl
ash and the control will lockout as
long as the fault remains. This lockout will automatically
reset if the hardware fault clears.
7. Power Interruption
During a momentary power interruption or at voltage lev-
els below the minimum operating voltage (line voltage or
low voltage) the system will self-recover when voltage re-
turns to the operating range.
Power interruptions of less than 80mS shall not cause the
control to change operating states. Power interruptions
greater than 80mS may cause interruption of the operat-
ing cycle and re-start.
NOTE:
80mS power interruption may cause gas valve to
close. If
fl
ame sense is lost, control will go to Ignition Re-
cycle.
8. Status Indicators
See Service Technician’s Manual for Control Module
Troubleshooting.
