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IX. STEP 9 — ADJUST EVAPORATOR-FAN SPEED
Adjust evaporator-fan rpm to meet jobsite conditions. Table 8
shows fan rpm at motor pulley settings. Table 9 shows motor
performance. Refer to Tables 10-33 to determine fan speed
settings.
A. Direct-Drive Motors
The evaporator-fan motor factory speed setting is shown on
label diagram affixed to base unit. If other than factory set-
ting is desired, refer to label diagram for motor reconnection.
See Fig. 33 for direct drive motor location.
B. Belt-Drive Motors
Fan motor pulleys are factory set for speed shown in Table 1.
See Fig. 34 for belt drive motor location.
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 and tag disconnect.
2. Loosen belt by loosening fan motor mounting nuts.
See Fig. 34.
3. Loosen movable pulley flange setscrew (see Fig. 35).
4. Screw movable flange toward fixed flange to increase
speed and away from fixed flange to decrease speed.
Increasing fan speed increases load on motor. Do not
exceed 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:
1. Loosen fan pulley setscrews.
2. Slide fan pulley along fan shaft.
3. 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 lb of
force).
3. Tighten motor mounting nuts.
4. Adjust bolt and tighten nut to secure motor in fixed
position.
Fig. 33 — Direct-Drive Motor Mounting
MOTOR MOUNTING
PLATE NUTS
Fig. 34 — Belt Drive Motor Mounting
Fig. 35 — Evaporator-Fan Pulley Adjustment