39
the warm-up period as follows: If ignition is
successful the warm-up is reduced by 3-
seconds on each subsequent call for heat until
ignition failure occurs. Upon ignition failure, the
warm-up is increased by 3-seconds on the
next try. If successful, the timing remains fixed
at this level. In general, whenever ignition failure
occurs the warm-up interval is increased by
3-seconds on the next try. And if successful, it
remains there. Minimum and maximum warm-
up time limits are set at 6 and 54-seconds,
respectively.
7. The furnace control must prove flame via the
flame sensor 5 seconds after the gas valve
opens. If flame is sensed, all burners are on and
the igniter cools off. If no flame is sensed, the gas
valve closes immediately and the inducer con-
tinues to run. A second trial for ignition (step 6)
begins if no flame is sensed on the fifth try for
ignition, the furnace control is locked and the red
LED will blink 4 times repetitively. The thermo-
stat must be opened for at least ten seconds to
reset the furnace control after a lock out.
Otherwise, the furnace will attempt another
ignition sequence in 1 hour.
8. The furnace control energizes the circulating
air blower on the heating speed 30 seconds
after the gas valve circuit is energized .
9. When the thermostat has been satisfied, gas
valve is de-energized.
10. The inducer is de-energized after a 30-second
postpurge.
11. The furnace control keeps the circulating air
blower energized for 120 seconds (factory set)
or 60, 90, or 180 seconds (field adjustable).
(See Figure 34.)
12. Abnormal conditions: If a limit opens during
operation, the inducer and circulating air blower
continue to operate. The gas valve is de-
energized immediately. The blowers continue
to operate until the limit closes. When the limit
closes the inducer blower is de-energized
immediately. The circulating air blower contin-
ues to operate for the specified delay (factory
set at 120 seconds).
Cooling Mode:
1. On a call for cooling the thermostat closes,
applying 24 VAC to the G and Y terminals on the
furnace control. This closes the compressor
contactor.
2. The furnace control energizes the circulating
blower (115 VAC) on the cooling speed.
3. When the thermostat is satisfied, the G and Y
terminals on the control board are de-energized
opening the compressor contactor.
4. The circulating air blower is de-energized after
a 90-second delay.
Fan Mode:
1. On a call for fan operation, the thermostat
applies 24 VAC to the G terminal on the furnace
control board.
2. The circulating air blower is energized immedi-
ately on the low heating speed.
3. If the furnace is operated in the continuous ON
position at the thermostat and is then switched
to AUTO, the circulating blower will operate for
a specified delay (factory set at 120 seconds).
Furnace Fails to Operate
If the furnace does not operate check the
following:
1. Is the thermostat operating properly?
2. Are the blower compartment door(s) in place?
3. Is the furnace disconnect closed?
4. Has the circuit breaker tripped or the control
board fuse burned open?
5. Is the gas turned on?
6. Are any manual reset switches open?
7. Is the filter dirty or plugged?
8. Is the flame sensor coated? (Remove and
clean with emery cloth.)
If the furnace locks out after 5 attempts for
ignition, it will try again every hour if a call for heat
remains. If the inducer and circulating air blow-
ers are operating, and items 1 through 8 have
been checked, press the red reset button on the
vent safety switch (See Figure 36). If the fur-
nace operates after depressing the reset but-
ton, contact a qualified serviceman to identify
and repair the problem.
If the furnace continues to not operate, depress
the red reset buttons on the flame roll-out
switches. (See Figure 36.) If the furnace oper-
ates after depressing the reset buttons, contact
a qualified servicemen to identify and repair the
problem.
Twinning
The two-stage furnace may not be twinned.
Summary of Contents for TA-060C-08A
Page 2: ...2...
