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127421-YIM-C-0606
Unitary Products Group
25
PHASING
Predator
®
units are properly phased at the factory. Check for
proper compressor rotation. If the blower or compressors
rotate in the wrong direction at start-up, the electrical connec-
tion to the unit is misphased. Change the phasing of the
field
line connection at the factory or field supplied discon-
nect
to obtain proper rotation. (Scroll compressors operate in
only one direction. If the scroll is drawing low amperage, has
similar suction and discharge pressures, or producing a high
noise level, the scroll is misphased). Units with scroll com-
pressors have a phase monitor as standard equipment. This
phase monitor will prevent unit operation under misphased
conditions by breaking the 24 volt power.
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 ‘PHASING’).
BELT TENSION
The tension on the belt should be adjusted as shown in
Figure 22.
Scroll compressors require proper rotation to oper-
ate correctly. Units are properly phased at the fac-
tory. Do not change the internal wiring to make the
blower condenser fans, or compressor rotate cor-
rectly.
TABLE 21: SUPPLY AIR LIMITATIONS
Unit Size
Minimum
Maximum
078
1950
3250
090
2250
3750
102
2250
4250
120
3000
5000
150
3750
6250
FIGURE 22 - BELT ADJUSTMENT
Procedure for adjusting belt tension:
1. Loosen six nuts (top and bottom) A.
2. Adjust by turning (B).
3. Never loosen nuts (C).
4. Use belt tension checker to apply a perpendicular force to
one belt at the midpoint of the span as shown. Deflection
distance of 4mm (5/32”) is obtained.
To determine the deflection distance from normal position,
use a straight edge from sheave to sheave as reference
line. The recommended deflection force is as follows:
Tension new belts at the max. deflection force recom-
mended for the belt section. Check the belt tension at least
two times during the first 24 hours of operation. Any reten-
sioning should fall between the min. and max. deflection
force values.
5. After adjusting retighten nuts (A).
A
A
A
B
SPAN LENGTH
DEFL. FORCE
C*
* NEVER LOOSEN