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19
Step 9 — Adjust Evaporator-Fan Speed —
Ad-
just evaporator-fan speed to meet jobsite conditions.
Tables 5A and 5B show fan rpm at motor pulley settings.
Tables 6 and 7 show maximum amp draw of belt-drive motor.
Table 8 shows motor nominal horsepower for evaporator-fan
motors. Refer to Tables 8-25 for performance data. See Tables
26 and 27 for accessory and option static pressure drops.
BELT-DRIVE MOTORS — Fan motor pulleys are factory set
for speed shown in Table 1. Check pulley alignment and belt
tension prior to start-up.
NOTE: Before adjusting fan speed, make sure the new fan
speed will provide an air temperature rise range as shown in
Table 1.
To change fan speed:
1. Shut off unit power supply, tag disconnect.
2. Loosen belt by loosening fan motor mounting nuts. See
Fig. 37.
3. Loosen movable pulley flange setscrew (see Fig. 38).
4. Screw movable flange toward fixed flange to increase
speed and away from fixed flange to decrease speed. In-
creasing fan speed increases load on motor. Do not ex-
ceed maximum speed specified in Table 1.
5. Set movable flange at nearest keyway of pulley hub and
tighten setscrew. (See Table 1 for speed change for each
full turn of pulley flange.)
To align fan and motor pulleys, loosen fan pulley setscrews
and slide fan pulley along fan shaft. Make angular alignment
by loosening motor from mounting.
To adjust belt tension:
1. Loosen fan motor mounting nuts.
2. Slide motor mounting plate away from fan scroll for
proper belt tension (1/2-in. deflection with 8 to 10 lbs of
force) and tighten mounting nuts.
3. Adjust lock bolt and nut on mounting plate to secure mo-
tor in fixed position.
MOTOR MOUNTING
PLATE NUTS
Fig. 37 — Belt-Drive Motor Mounting
Fig. 38 — Evaporator-Fan Pulley Adjustment