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Installation, Operation & Maintenance Manual ( IOPCKKS60220510C1)
i.e. Y1 to Y1, Y2 to Y2,Y3 to Y3 & Y4 to Y4.
7.
If 24 volts is present at the UCB Y1 terminal, the compressor
may be out due to an open high pressure switch, low pressure
switch, or freezestat. Check for 24 volts at the HPS1, LPS1,
and FS1 terminals of the UCB. If a switch has opened, there
should be a voltage potential between the UCB terminals, e.g.
if LPS1 has opened, there will be a 24 volt potential between
the LPS1 terminals.
8.
If 24 volts is present at the UCB Y1 terminal and none of the
protection switches have opened, the UCB may have locked
out the compressor for repeat trips. The UCB should be
flashing an alarm code. If not, press and release the ALARMS
button on the UCB. The UCB will flash the last five alarms on
the LED. If the compressor is locked out, cancel any call for
cooling. This will reset any compressor lock outs.
NOTE : While the above step will reset any lockouts,
compressor # 1 may be held off for the ASCD. See the next
step.
9.
If 24 volts is present at the UCB Y1 terminal and none of the
switches are open and the compressor is not locked out, the
UCB may have the compressor in an ASCD. Check the LED for
an indication of an ASCD cycle. The ASCD should time out
within 5 minutes. Press and release the TEST button to reset
all ASCDs.
10.
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.
11. If none of the above correct the error, replace the UCB.
* On calls for the second stage of cooling, the supply air
blower motor and compressor # 1 are operating but
compressor # 2 is not (the room thermostat fan switch is in
the "AUTO" position).
1.
Compressor # 2 will not energize simultaneously with
compressor #1 if a call for both stages of cooling is received.
The UCB delays compressor # 2 by 30 seconds to prevent
a power surge. If after the delay compressor # 2 does not
energize on a second stage call for cooling, check for line
voltage at the compressor contactor 2, and that the contactor
is pulled in. Check for loose wiring between the contactor and
the compressor.
2.
If compressor contactor 2 is pulled in and voltage issupplied,
lightly touch the compressor housing. If it is
compressor may be off on inherent protection. Cancel any
calls for cooling and wait for the internal overload to reset.
3.
Test again when cool.
4.
If compressor contactor 2 is not pulled in, check for 24 volts
at the compressor contactor coil. If 24 volts is present and
compressor contactor is not pulled in, replace the contactor.
5.
Failing the above, if voltage is supplied at compressor
6.
contactor 2, and it is pulled in, and the compressor still
does not operate, replace the compressor. 5. If 24 volts is
not present at compressor contactor 2, check for 24 volts at
the UCB terminal, C2. If 24 volts are present, check for loose
wiring between C2 and the compressor contactor.
7.
If 24 volts is not present at the C2 terminal, check for 24 volts
UCB,
from the room thermostat at the UCB Y2 terminal. If 24 volts is
not present from the room thermostat, check for the following :
and
the
8.
If 24 volts is present at the UCB Y2 terminal, the compressor
may be out due to an open high pressure switch, low pressure
switch, or freezestat. Check for 24 volts at the HPS2, LPS2,
and FS2 terminals of the UCB. If a switch has opened, there
should be a voltage potential between the UCB terminals,
e.g. if LPS2 has opened, there will be 24 volts of potential
between the LPS2 terminals.
9.
If 24 volts is present at the UCB Y2 terminal and none of
the protection switches have opened, the UCB may have
locked out the compressor for repeat trips. The UCB should
be flashing a code. If not, press and release the ALARMS
button on the UCB. The UCB will flash the last five alarms on
the LED. If the compressor is locked out, remove any call for
cooling at the thermostat or by disconnecting the thermostat
wiring at the Y2 UCB terminal. This will reset any Installation,
compressor lock outs.
NOTE : While the above step will reset any lock outs,
compressor # 1 will be held off for the ASCD, and compressor
# 2 may be held off for a portion of the ASCD.
See the next step.
10.
If 24 volts is present at the UCB Y2 terminal and none of the
switches are open and the compressor is not locked out, the
UCB may have the compressor in an ASCD. Check the LED
for an indication of an ASCD cycle. The ASCD should time
out within 5 minutes. Press and release the TEST button to
reset all ASCDs.
11.
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. Local distributors
can test the UCB for this programming.
12.
If none of the above corrected the error, test the integrity of
the UCB. Disconnect the C2 terminal wire and jumper it to
the Y2 terminal. DO NOT jump the Y2 to C2 terminals. If the
compressor engages, the UCB has faulted.
13.
If none of the above correct the error, replace the UCB.
* On a call for cooling, the supply air blower motor and
compressor # 2 are operating but compressor # 1 is not (the
room thermostat fan switch is in the "AUTO" position).
1.
Compressor # 2 is energized in place of compressor # 1 when
hot, the
compressor # 1 is unavailable for cooling calls. Check the UCB
for alarms indicating that compressor # 1 is locked out. Press
and release the ALARMS button if the LED is not flashing an
alarm.
2.
Check for line voltage at the compressor contactor 1, and that
the contactor is pulled in. Check for loose wiring between the
contactor and the compressor.
3.
If compressor contactor 1 is pulled in and voltage is supplied
at the contactor 1, lightly touch the compressor housing. If
it is hot, the compressor may be off on inherent protection.
Cancel any calls for cooling and wait for the internal overload
to reset. Test again when cool.
UCB,
i.e.
Y1
to
Y1,
Y2
to
Y2.
Page 22
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