Specifications

177008-YIM-A-0406
Unitary Products Group 47
mounted above the ICB. First verify that the relay is pulled
in by visual inspection. If not, then verify the minimum
voltage is present between terminals “A” and “B” of the
relay. If the minimum voltage is not present, then check the
wiring. If it is present, then verify that a minimum of 150
volts is present at terminals “5” and “7” of the draft motor
relay. If not present at terminal “7” of the draft motor relay,
then troubleshoot the transformer in blower section and its
wiring. If present at terminal “7” and not at terminal “5” of
the draft motor relay, then the relay is at fault. If the
minimum voltage is present at terminal 5 of the draft motor
relay, then the draft motor is at fault.
The ignitor sparks at the pilot burner but the pilot does not ignite
and a gas odor is detected at the draft motor outlet.
1. Adjust the pilot adjust screw on the gas valve as described
in “PILOT CHECKOUT” on page 39.
2. Check the supply pressure as described in “POST START
CHECK LIST” on page 38. Make adjustments as
necessary.
3. Check the pilot orifice and pilot burner for obstruction as
described in paragraph above. Clean as needed but the
problem should not be the gas valve.
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” on page 39.
2. Check the supply pressure as described in “POST START
CHECK LIST” on page 38. Make adjustments as
necessary.
3. Make sure that the pilot burner is not bent or damaged.
4. Make sure that the ground connections at the pilot burner,
gas valve and ignition control are intact. Check the ignitor
wire for good electrical connection. If all are intact, replace
the ignition control.
The pilot burner lights and the spark stops but the main burners
do not light.
1. Check electrical connections between the ignition control
and the gas valve. If intact, check for 24 volts across
terminals “MV” and “GROUND” terminals. If no voltage
detected, replace ignition control. If voltage is present,
replace gas valve.
Main burners light but exhibit erratic flame characteristics.
1. Adjust air shutters as described in “BURNER AIR
SHUTTER ADJUSTMENT” on page 40.
2. Check the main burner orifices for obstruction and
alignment. Removal procedure is described in BURNER
INSTRUCTIONS on page 39. Clean or replace burner
orifices and burners as needed.
Unit Flash Codes
Various flash codes are utilized by the unit control board (UCB)
and the ignition control board (ICB) 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 boards flashes a 1 second on, 1 second
off “heartbeat” during normal operation. This is to verify that the
UCB and the ICB are 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 approximately 2 seconds.
Current alarms or active restrictions are flashed on the ICB
LED. No history is stored on the ICB.
In some cases, it may be necessary to “zero” the ASCD for the
compressors in order to perform troubleshooting. To reset all
ASCDs for one cycle, press and release the UCB TEST button
once.
Table 24: 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
5 Flashes LPS1 - Compressor Lock out
7 Flashes FS1 - 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
13 Flashes Compressor Held Off Due To Low Voltage
1
14 Flashes EEPROM Storage Failure (Control Failure)
OFF No Power or Control Failure
Table 25: Ignition Control Board Flash Codes
Flash Code Description
On Steady Control Failure - Replace Control
Heart Beat Normal Operation
1 Flash Not Applicable
2 Flashes Pressure / Centrifugal Switch Open with Inducer On
3 Flashes
Pressure / Centrifugal Switch Closed with Inducer
Off
4 Flashes Not Applicable
5 Flashes Lock Out From Too Many Flame Losses
6 Flashes High Temperature Switch Open (Primary or Aux.)
7 Flashes Rollout Switch Open
8 Flashes Flame Present With Gas OFF