York ZF 180 Series Installation Manual page 45

from Y1 "OUT" for incorrect wiring. If 24 volts is not present
at the Y1 "OUT" terminal, the UCB must be replaced.
12. For units without economizers: If 24 volts is present at the
Y1 "OUT" terminal, check for 24 volts at the Y1 "ECON"
terminal. If 24 volts is not present, check for loose wiring
from the Y1 "OUT" terminal to the Mate-N-Lock plug, the
jumper in the Mate-N-Lock plug, and in the wiring from the
Mate-N-Lock plug to the Y1 "ECON" terminal.
For units with economizers: If 24 volts is present at the Y1
"OUT" terminal, check for 24 volts at the Y1 "ECON"
terminal. If 24 volts is not present, check for loose wiring
from the Y1 "OUT" terminal to the Mate-N-Lock plug, a
poor connection between the UCB and economizer Mate-
N-Lock plugs, loose wiring from the Mate-N-Lock plug to
the economizer, back to the Mate-N-Lock plug, and from
the Mate-N-Lock plug to the Y1 "ECON" terminal. The
economizer control may have faulted and is not returning
the 24 volts to the Y1 "ECON" terminal even though the
economizer is not providing free cooling. To test the
economizer control, disconnect the Mate-N-Locks and
jumper between the WHITE and YELLOW wires of the
UCB's Mate-N-Lock plug.
13. The UCB can be programmed to lock out compressor
operation during free cooling and in low ambient
conditions. These options are not enabled by default. They
can be checked by local distributors.
For units with factory installed economizers, the UCB is
programmed to lock out compressor operation when the
LAS set point is reached.
For units without factory installed or with field installed
economizers, the UCB allows compressor operation all the
time. This programming can be checked or changed by the
local distributor.
14. If none of the above corrected the error, test the integrity of
the UCB. Disconnect the C1 terminal wire and jumper it to
the Y1 terminal. DO NOT jump the Y1 to C1 terminals. If
the compressor engages, the UCB has faulted.
15. If none of the above correct the error, replace the UCB.
Gas Heat Troubleshooting Guide
On calls for heating, the draft motor operates and the furnace
lights but the supply air blower motor does not energize after a
short delay (the room thermostat fan switch is in "AUTO"
position).
Johnson Controls Unitary Products
The furnace may shut down on a high temperature
condition during the procedure. If this occurs, the UCB
energize the supply air blower motor until the high
temperature limit has reset. Caution should be used at
all times as the supply air blower may energize
regardless of the room thermostat fan switch position.
For troubleshooting of optional VFD, disconnect all
power to the drive. Be aware that high voltages are
present in the drive even after power has been
disconnected. Capacitors within the drive must be
allowed to discharge before beginning service.
1. Place the thermostat fan switch in the "ON" position. If the
supply air blower motor energizes, go to Step 9.
2. If the supply air blower motor does not energize when the
fan switch is set to "ON," ch eck that line voltage is being
supplied to the contacts of the M3 contactor, and that the
contactor is pulled in. For units with VFD, check that line
voltage is being supplied to the M3-Auxiliary contacts.
Check for loose wiring between the contactor and the
supply air blower motor.
3. If M3 is pulled in and voltage is supplied at M3, lightly touch
the supply air blower motor housing. If it is hot, the motor
may be off on inherent protection. Cancel any thermostat
calls and set the fan switch to "AUTO", wait for the internal
overload to reset. Test again when cool.
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 connections 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 terminal, check for loose
wiring between the UCB and M3.
a. 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:
• 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.)
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