127915-YIM-A-0405
Unitary Products Group
73
The pilot burner ignites but the ignitor continues to
spark and the main burners do not ignite.
1.
Make the same checks and adjustment as
described in “PILOT CHECKOUT” page 65.
2.
Check the supply pressure as described in “POST
START CHECK LIST” page 64. Make adjustments
as necessary.
3.
Make sure that the pilot burner is not bent or dam-
aged.
4.
Make sure that the ground connections at the pilot
burner, gas valve and ignitor control are intact.
Check the high tension wire for good electrical con-
nection. If all are intact, replace the ignitor module.
The pilot burner lights and the spark stops but the main
burners do not light.
1.
Check electrical connections between the ignitor
control and the gas valve. If intact, check for 24
volts across terminals “MV” and “COMMON” termi-
nals. If no voltage detected, replace ignitor control.
If voltage is present, replace gas valve.
Furnace lights with roll-out or one burner has delayed
ignition.
1.
Make sure that the carryover is aligned properly
with the flame sensor as described in “PILOT
CHECKOUT” page 65.
Main burners light but exhibit erratic flame characteris-
tics.
1.
Adjust air shutters as described in “BURNER AIR
SHUTTER ADJUSTMENT” page 65.
2.
Check the main burner orifices for obstruction and
alignment. Removal procedure is described in
BURNER INSTRUCTIONS page 65. Clean or
replace burner orifices and burners as needed.
UNIT FLASH CODES
Various flash codes are utilized by the unit control
board (UCB) to aid in troubleshooting. Flash codes are
distinguished by the short on and off cycle used
(approximately 200ms on and 200ms off). To show
normal operation, the control board flashes a 1 second
on, 1 second off "heartbeat" during normal operation.
This is to verify that the UCB is functioning correctly.
Do not confuse this with an error flash code. To prevent
confusion, a 1-flash, flash code is not used.
Current alarms or active restrictions are flashed on the
UCB LED. Pressing and releasing the ALARMS button
on the UCB can check the alarm history. The UCB will
cycle through the last five (5) alarms, most recent to
oldest, separating each alarm flash code by approxi-
mately 2 seconds.
In some cases, it may be necessary to "zero" the
ASCD for the compressors in order to perform trouble-
shooting. To reset all ASCDs for one cycle, press and
release the UCB TEST button once.
The control will flash 250ms on and 250ms off for sta-
tus codes. The control will separate the flash codes
with a 2 second off delay between flash codes. Under
normal operation, the control will flash the LED at a
rate of, 1 second on and 1 second off. This will be the
“Heart Beat”.
TABLE 33: UNIT CONTROL BOARD FLASH CODES
Flash Code
Description
On Steady
Control Failure - Replace Control
Heart Beat
Normal Operation
1 Flash
Not Applicable
2 Flashes
Control waiting ASCD
1
1.
These flash codes do not represent alarms.
3 Flashes
HPS1 - Compressor Lock out
4 Flashes
HPS2 - Compressor Lock out
5 Flashes
LPS1 - Compressor Lock out
6 Flashes
LPS2 - Compressor Lock out
7 Flashes
FS1 - Compressor Lock out
8 Flashes
FS2 - Compressor Lock out
9 Flashes
Ignition Control Locked Out/
Ignition Control Failure / Limit Switch Trip /
No Jumper Plug in Heat Section
10 Flashes
Compressors Locked Out On Low
Outdoor Air Temperature
1
11 Flashes
Compressors Locked Out Because The
Economizer Is Using Free Cooling
1
12 Flashes
Fan Overload Switch Trip
13 Flashes
Compressor Held Off Due To Low Voltage
1
14 Flashes
EEPROM Storage Failure (Control Failure)
OFF
No Power or Control Failure
