Carrier 48LJD - Manual (Page 13)

OUTDOOR AIRFLOW (cfm x 100)
Example:
Given —
Return-Air Negative Static Pressure .........................0 2 in wg
Outdoor Air ...................................................... 900 cfm
Determine —
Setting = 5
Fig. 22 — Economizer Damper Minimum Position Setting
Fig. 23 - Minimum Position Damper Setting
Step 9 — Adjust Evaporator-Fan Speed — Ad­
just evaporator-fan speed to meet jobsite conditions.
Table 3 shows fan rpm at motor pulley settings. Refer to
Tables 4-15 to determine fan speed settings.
DIRECT DRIVE MOTORS — The evaporator-fan motor
factory speed setting is shown on label diagram affixed to
base unit. If other than factory setting is desired, refer to
label diagram for motor reconnection.
BELT DRIVE MOTORS — Ean motor pulleys are factory
set for speed shown in Table 1.
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.
2. Loosen belt by loosening fan motor mounting nuts. See
Fig. 26.
3. Loosen movable pulley flange setscrew (see Fig. 27).
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 key way of pulley hub and
tighten setscrew. (See Table 1 for speed change for each
full turn of pulley flange.)
13