York DM150 User Manual
Page 26
127408-YIM-B-0606
26
Unitary Products Group
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.)
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 25.
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 17: SUPPLY AIR LIMITATIONS
Unit Size
Minimum
CFM (m
3
/sec)
Maximum
CFM (m
3
/sec)
090
2250 (1)
3750 (1.7)
120
3000 (1.4)
5000 (2.3)
150
3750 (1.7)
6250 (2.9)
FIGURE 25 - 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 rec-
ommended for the belt section. Check the belt ten-
sion at least two times during the first 24 hours of
operation. Any retensioning 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