WSHP-SVX015C-EN
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motor is factory wired to operate on speed tap 1 during
cooling. For 3 & 4 ton electric units operating in heat
mode, the minimum setting is Tap 4.
For these units, a separate tap terminal is provided to
change speeds automatically between heating and
cooling. The motor can be rewired for different speed
settings should the application require it. Refer to the
wiring diagram that shipped in the unit and the unit fan
performance tables in the Service Facts.
The indoor fan motors are specifically designed to
operate within the BHP parameters listed in the fan
performance tables of the unit service facts.
When verifying direct drive fan performance, the tables
must be used somewhat differently than those of belt
driven fans. Fan performance diagnostics can be easily
recognized when these tables are used correctly.
Before starting the SERVICE TEST, set the minimum
position setpoint for the economizer to 0% using the
setpoint potentiometer located on the Economizer
Control (ECA), if applicable.
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Using the service test guide for component operation
in the Pre-Start section, momentarily jump across the
Test 1 & Test 2 terminals on LTB1 one time to start the
Minimum Ventilation Test.
Verifying Proper Air Flow (Units
with Belt Drive Indoor Fan)
Much of the systems performance and reliability is
closely associated with, and dependent upon having
the proper airflow supplied both to the space that is
being conditioned and across the evaporator coil.
The indoor fan speed is changed by opening or closing
the adjustable motor sheave.
Before starting the SERVICE TEST, set the minimum
position setpoint for the economizer to 0 percent using
the setpoint potentiometer located on the Economizer
Control (ECA), if applicable.
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Using the Service Test Guide in the Service test guide
for component operation, momentarily jump across
the Test 1 & Test 2 terminals on LTB1 one time to start
the Minimum Ventilation Test.
Once the supply fan has started, check for proper
rotation. The direction of rotation is indicated by an
arrow on the fan housing.
With the fan operating properly, determine the total
system airflow (CFM) by;
1. Measuring the actual RPM,
2. Measure the amperage at the supply fan contactor
and compare it with the full load amp (FLA) rating
stamped on the motor nameplate.
a. Calculate the theoretical BHP
Actual Motor Amps X Motor HP
Motor Nameplate Amps
b. Using the fan performance tables in the unit
Service Facts, plot the actual RPM (step 1) and
the BHP (step 2a) to obtain the operating CFM.
3. If the required CFM is too low, (external static
pressure is high causing motor HP output to be
below table value),
a. Relieve supply and/or return duct static.
b. Change indoor fan speed and repeat steps 1 and
2.
•
To Increase Fan RPM; Loosen the pulley adjustment
set screw and turn sheave clockwise.
•
To Decrease Fan RPM; Loosen the pulley
adjustment set screw and turn sheave
counterclockwise.
•
If the required CFM is too high, (external static
pressure is low causing motor HP output to be
above table value), change indoor fan speed and
repeat steps 1 and 2.
•
To stop the SERVICE TEST, turn the main power
disconnect switch to the “Off” position or proceed
to the next component start-up procedure. Remove
electro mechanical test mode connections (if
applicable).
Return Air Smoke Detector
The return air smoke detector is designed to shut off
the unit if smoke is sensed in the return air stream.
Sampling the airflow entering the unit at the return air
opening performs this function.
In order for the smoke detector to properly sense
smoke in the return air stream, the air velocity entering
the unit must be between 500 and 4000 feet per minute.
Equipment covered in this manual will develop an
airflow velocity that falls within these limits over the
entire airflow range specified in the evaporator fan
performance tables.
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