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Step 14 — Fan Speed Set Up
UNITS WITH ELECTRO-MECHANICAL CONTROLS
The Fan Speed set up controls are located on the lower
section of the Unit Control Board (UCB). See Fig. 50 for
location.
1. Check the job specifications for the CFM (cubic feet
per minute) and ESP (external static pressure)
required.
2. Using the chart on the Fan Speed Set Up labels (see
Fig. 51), calculate the Vdc from the CFM and ESP for
the base unit plus any field accessories (as listed on
the label).
NOTE: The Fan Speed Set Up labels are located on the
High Voltage cover in the Control Box.
3. Connect a multimeter to the Vdc terminals on the
UCB.
4. Set the Range Switch to either A, B, or C per the
Switch Range table.
5. Using a straight blade screwdriver turn the Vdc con-
trol dial to fine tune the Vdc reading.
6. Record the reading in the Field Setting field.
Low Speed Fan Adjustment
2-Pin DIP Switch
The Low Speed 2-Pin DIP switch is located near the center
of the UCB. See Fig. 50.
Units are pre-set at the factory for a low speed fan setting of
75% (DIP1 On, DIP2 Off). The factory default setting is
shown on the unit's control wiring label diagram. See Table
13 for the various Low Speed settings.
Table 13 — Low Speed 2-Pin DIP Switch Settings
LOW SPEED
DIP1
DIP2
0
0
0
1
1
0
1
1
38
Economizer
Fig. 49 — EconoMi$er
% of User Set Fan Speed
100%
88%
75%
66%
Specifications subject to change without notice.
Unit Without Economizer or
2 Position Damper
2 Position Damper
IV Wiring
®
FAN SPEED SET UP CONTROLS
Fig. 50 — UCB Fan Speed Controls
38
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