York CURBPAK CP23 Installation Operation & Maintenance page 64

Service
CFM LOWER THAN REQUIRED
CFM HIGHER THAN REQUIRED
MOTOR -HIGH CURRENT DRAW
MOTOR - UNBALANCED
CURRENT DRAW
64
Dampers closed and / or splitter rod disconnected. Open dampers and
connect splitter rod.
Registers closed. Open registers.
Fire damper(s) closed. Open fire damper(s).
Insulating duct liner loose. Reattach loose duct liner.
Leaks in supply ducts caused by open seams or holes in ductwork. Repair
seams and / or leaks in duct system.
Air filters dirty or clogged. Remove clogging debris and / or clean filters.
Coils dirty or clogged. Remove clogging debris and / or clean coils.
System not balanced properly. Balance system per design specifications.
Pay close attention to External Static Pressure "Design" Vs. "Actual".
Not enough length of straight duct at fan outlet before turn or restriction.
Increase length of straight duct at fan outlet or increase fan RPM to offset
performance loss. Note: Observe fan RPM limits per manufacturers
guidelines.
Obstructions in fan discharge duct. Remove obstructions.
Oversized ductwork. Reduce duct sizes or decrease fan RPM to obtain
desired flow.
Unit access door open. Close all unit access doors.
System not balanced properly. Balance system per design specifications.
Pay close attention to External Static Pressure "Design" Vs. "Actual".
Registers or grilles not installed. Install all registers and grilles per design
specifications.
Unit air filters not in place. Install air filters.
Take ammeter readings on all three phases of motor to verify accuracy of
ammeter.
High line voltage. Consult power company. Could possibly reduce voltage
by using lower transformer tap.
Motor overloaded. Reduce load or use larger HP motor.
Low line voltage. Consult power company. Could possibly increase voltage
by using high transformer tap.
Unbalanced line voltage due to power supply, unbalanced electrical
system loading in building, high resistance connection or undersized
power supply lines. Carefully check voltage across each phase at the
motor terminals with a quality, properly calibrated voltmeter. If the voltage
per phase is more than 1 % out of balance, the current will be out of
balance by an even greater percentage.
If in doubt as to whether the problem is with the motor or incoming power
supply lines perform the following test: Rotate all three input power lines
to the motor by one position - i.e., move line #1 to motor lead #2, line #2
to motor lead #3 and line #3 to motor lead #1. If the unbalanced current
draw pattern follows the input power lines the problem is the power
supply. Correct the voltage balance of the power supply. If the unbal-
anced current draw pattern follows the motor leads the problem is a
defective motor. Replace motor.
YORK INTERNATIONAL