York International ZQ Series, Installation Manual

Page: 43 / 92

CAUTION
When installing equipment in a facility with a 3 phase
high-leg delta power supply, care must be taken to
ensure that the high-leg conductor is not attached to
either of the two legs of the (single phase, direct drive)
X13 or ECM motors. Failure to do so can result in the
motor acting erratically or not running at all.
Check for the high leg conductor by checking voltage
of each phase to ground.
Example: A or L1 phase to ground, voltage reading is
120V. B or L2 phase to ground, voltage reading is 195
to 208V. C or L3 phase to ground, voltage reading is
120V. Therefore B or L2 phase is the high Leg. The
high should always be wired to the center or B or L2
tap.
Note : Check all three phase motors and compressors
for proper rotation after making a change. If it is
necessary to change 3 phase motor rotation, swap A
or L1 and C or L3 only.
Blower Rotation
Check for proper supply air blower rotation. If the
blower is rotating backwards, the line voltage at the
unit point of power connection is misphased. See
Blower Phasing .
INSTALLATION MANUAL ZQ SERIES 3 - 5 ton 60 Hertz R-410A 43
Johnson Controls Ducted Systems