Unit Flash Codes; Fan On And Off Delays - York DM036 Installation Manual

motor is at fault. On 575 volt models, if voltage is present at
the terminal, then check the draft motor relay (DMR on
single stage gas heat and DMR-2 on two stage gas heat)
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 42.
2. Check the supply pressure as described in "POST START
CHECK LIST" on page 41. 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 42.
2. Check the supply pressure as described in "POST START
CHECK LIST" on page page 41. 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 42.
2. Check the main burner orifices for obstruction and
alignment. Removal procedure is described in BURNER
INSTRUCTIONS on page 42. Clean or replace burner
orifices and burners as needed.
Johnson Controls Unitary Products

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.
• LAST ERROR - When this button is pressed and released
one time within five seconds, it flashes the last five flash
codes on the board's LED. The most recent alarm is
shown first and the oldest alarm is shown last.
When pressed and released twice within a five second
span, the fault history is cleared.
• TEST RESET - When this button is pressed and released
one time within five seconds, any anti-short cycle delays
(ASCD) is by-passed for one cycle.
When this button is pressed twice within five seconds, any
active lockouts are reset.
• COMM SET UP - If the board is to be networked with
other units, this button is used to set the network address.
The first time the button is pressed within five seconds, it
scans the bus, then assigns itself the first available
address {starts at 2}. It then flashes that address one time.
Pressing the button two times within five seconds causes
the control to flash its address.
Pressing the button three times within five seconds forces
the control to reset its address to 1, which is the factory
default.
Current alarms or active restrictions are flashed on the ICB
LED. No history is stored on the ICB.

Fan On And Off Delays

The fan ON and OFF delays can be field adjusted by pressing a
combination of buttons on the UCB.
• Gas Heat Option #1 - Press the LAST ERROR and
TEST RESET buttons simultaneously and then release.
The control flashes three times as it writes a 30 second
delay ON and a 90 second delay OFF to the program.
• Gas Heat Option #2 - Press the COMM SETUP and
TEST RESET buttons simultaneously and then release.
The control flashes four times as it writes a 30 second
delay ON and a 180 second delay OFF to the program.
• Electric Heat - Press and release the COMM SETUP and
LAST ERROR buttons at the same time. The control
flashes twice on the LED as the control writes a 0 second
ON and a 30 second OFF fan delay to the control's
program memory.
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