Lennox ELITE 12GCS Series Unit Information page 10

Blower Operation / Fan Off Time
Fan off timing (time that the blower operates after the heat /cool
demand is satisfied) is factory set at 120 seconds for heat and
90 seconds for cool. These times are not adjustable. Fan on
time is factory set at 30 seconds for heat demand, following the
opening of the gas valve and 5 seconds for cool demand.
These times are not adjustable.
TABLE 1
IGNITION CONTROL JACK/PLUG TERMINAL DESIGNATIONS
PIN #
1
2
3
4
5
6
Thermostat Connection
Thermostat jackjplug connections are found on the control
board. The terminals are clearly marked with the correspond-
ing thermostat designation. (See figure 6)
Troubleshooting
The control board is equipped with a diagnostic green LED to
indicate mode of unit. The codes are given in table 2.
TABLE 2
IGNITION CONTROL DIAGNOSTIC CODES
Slow Flash Normal operation no call for heat
Fast Flash Normal operation call for heat
2 Flashes Lockout−failed to detect or sustain flame
3 Flashes Pressure switch open or closed / or auxila-
ry limit open*.
4 Flashes High limit or Rollout switch
open
5 Flashes Flame sensed and gas valve not
energized
Steady Circuit board self−check failure or ignition/
Flash blower control wired incorrectly
NOTE−This LED code will not appear until after the indoor blower has
been de−energized for approximately 120 seconds.
5− Blower Control A15 (CHP Only)
Blower control A15 is found in the control box of all 12CHP
units. The control is responsible for energizing the blower in re-
sponse to thermostat demand. The control has a set on delay
timing of 5 seconds and a set off timing of 90 seconds. These
timings are not adjustable.
FUNCTION
Rollout Switch Out
Pressure Switch
Gas Valve Out
Gas Valve Common
Secondary Limti Out
Rollout Switch Return
6−Defrost Control CMCI (CHP Only)
If outdoor ambient conditions are such that frost forms on
the outdoor coil, the defrost control monitors the need for
and initiates and terminates defrost cycles as necessary to
maintain system performance. The defrost control is time/
temperature initiated and temperature terminated with a
maximum defrost time (time−out) of 10 minutes. Time be-
tween defrost cycles is pre−set at 60−minute intervals at the
factory, but can be field adjusted between 30, 60 or 90 min-
utes. See figure 7 for field adjustment of defrost timing.
DEFROST CONTROL TEST AND
TIME PIN LOCATIONS
JUMPER SHOWN ON T2 PIN
DEFROST
TEST PINS
The defrost control will initiate a defrost cycle if time period
has elapsed and the defrost sensor detects a temperature
below freezing. At the start of defrost cycle, the defrost con-
trol will energize the reversing valve solenoid, shifting the
reversing valve and de−energizing the outdoor fan. The de-
frost relay will also close energizing optional electric heat
for increased comfort during defrost. The unit will remain in
the defrost mode until the defrost sensor has determined
that the frost has been removed from the coil or a 10−minute
time period has elapsed.
The defrost control is also equipped with a set of test pins to
aid in troubleshooting of the defrost system. The following is
a brief outline of the testing of the defrost system.
Defrost sensor will be closed at 32_F(0_C) or below. If tem-
peratures are such that switch is not closed, jumper be-
tween defrost sensor terminals on defrost control. The de-
frost sensor terminals are side by side and are labeled
"DFS."
Start System in Heating Operation.
Jumper test pins. A 1/4" quick connect terminal crimped
onto a solid wire or brazing rod works well for test jumper.
Jumping test pins speeds up time interval by a factor of
256.
Page 10
DEFROST TIME
PINS
T1 = 30 MINUTES
(T1, T2, T3)
T2 = 60 MINUTES
T3 = 90 MINUTES
FIGURE 7