York SUNLINE MagnaDRY DR240 Installation Manual page 72

284811-YIM-C-1008
4. If M3 is not pulled in, check for 24 volts at the M3
coil. If 24 volts is present at M3 but M3 is not pulled
in, replace the contactor.
5. Failing the above, if there is line voltage supplied at
M3, M3 is pulled in, and the supply air blower
motor still does not operate, replace the motor.
For units with VFD, if there is line voltage supplied
at M3, M3 is pulled in, and the blower motor does
not operate, check all power & control wiring con-
nections to and from the drive and for any fault/
warning messages displayed on the drive's digital
display (refer to the drive user manual for full
descriptions, if necessary). Clear any fault by
pressing 'RESET' on the drive's keypad and take
any corrective action as needed. If the motor still
does not operate, replace the motor.
6. If 24 volts is not present at M3, check that 24 volts
is present at the supply air blower motor terminal
on the UCB. If 24 volts is present at the UCB termi-
nal, check for loose wiring between the UCB and
M3.
7. If 24 volts is not present at the UCB supply air
blower motor terminal, check for 24 volts from the
room thermostat. If 24 volts is not present from the
room thermostat, check for the following:
a. Proper operation of the room thermostat (contact
between R and G with the fan switch in the "ON"
position and in the "AUTO" position during operation
calls).
b. Proper wiring between the room thermostat and the
UCB.
c. Loose wiring from the room thermostat to the UCB.
8. If 24 volts is present at the room thermostat but not
at the UCB, check for proper wiring between the
thermostat and the UCB, i.e. that the thermostat G
terminal is connected to the G terminal of the UCB,
and for loose wiring.
9. If the thermostat and UCB are properly wired,
replace the UCB.
10. If the blower motor runs with the fan switch in the
"ON" position but does not run shortly after the fur-
nace has ignited when the fan switch is in the
"AUTO" position, check the room thermostat for
contact between R and G during "W1" calls.
72
On calls for heating, the supply air blower operates but
the draft motor does not (the room thermostat fan
switch is in the "AUTO" position).
1. The draft motor has inherent protection. If the
motor shell is hot to the touch, wait for the internal
overload to reset.
2. If the motor shell is cold with the room thermostat
calling for heat, check for line voltage at the
motor's Mate-N-Lok connector attached to the
evaporator partition. If line voltage is present,
replace the draft motor.
3. If line voltage is not present, check for line voltage
at the heat relay (RW1) contacts in the main con-
trol box and check to see if the (RW1) is pulled in.
4. If the (RW1) relay is pulled in, check for a loose line
voltage connection.
5. If the (RW1) relay is not pulled in, check for 24 volts
at the (RW1) coil. If 24 volts is present, replace the
(RW1) relay. If 24 volts is not present, check for a
loose 24 volt connection back to the relay board
and check the connections from the room thermo-
stat to the relay board. If all connections are cor-
rect, replace the relay board.
The draft motor runs but the furnace does not light and
the sparker does not spark.
1. The ignition control (IC1, IC2) may be locked out
due to either a flame roll out or 100% shut off.
These safety features are described above. If lock-
out has occurred, 24V must be removed from the
ignition controls. This is done at the unit or by
resetting the room thermostat. After resetting 24V,
check for proper furnace operation. If lock-out con-
tinues to occur, locate the source of the problem
and correct.
2. Check all 24 volt connections from the relay board
to and in the gas heat section. Check low voltage
connections to the (ETD) located in the control
box.
3. If the furnace is hot, it may be out on an over-tem-
perature condition, wait for limit reset.
4. If the furnace is cold, check for 24 volts at wire 241
attached to the electrical time delay (ETD) located
in the main control box. If 24 volts is not found,
replace the ETD.
Johnson Controls Unitary Products