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Subject to change without notice. Printed in U.S.A. 66307-YIM-B-0606
Copyright © 2006 by Unitary Products Group. All rights reserved. Supersedes: 66307-YIM-A-0704/035-17277-004-A-0704
Unitary 5005 Norman
Products York OK
Group Drive 73069
present, trace the wiring from Y1 “OUT” for incorrect wir-
ing. 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” termi-
nal. 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 condi-
tions. 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 termi-
nals. If the compressor engages, the UCB has faulted.
15. If none of the above correct the error, replace the UCB.