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5. Ensure all electrical equipment and controls are properly
grounded in accordance with job drawings, certified
drawings, and all applicable electrical codes.
6. Ensure the customer’s contractor has verified proper op-
eration of the pumps, cooling tower fans, and associated
auxiliary equipment. This includes ensuring motors are
properly lubricated and have proper electrical supply and
proper rotation. Carrier must maintain pump control for
freeze protection algorithm.
7. For machines that are being serviced (not required for
new startups supplied by factory), test the chiller com-
pressor motor and its power lead insulation resistance
with an insulation tester such as a megohmmeter. (Use a
tester rated for motor voltage.)
a. With the tester connected to the motor leads, take
10-second and 60-second megohm readings.
b. Divide the 60-second resistance reading by the
10-second reading. The ratio, or polarization
index, must be one or higher. Both the 10 and
60-second readings must be at least 50 megohms.
If the readings on a field-installed starter are unsatis-
factory, repeat the test at the motor with the power
leads disconnected. Satisfactory readings in this sec-
ond test indicate the fault is in the power leads.
Check Purge Compressor Operation — Enter
Quick Test menu (under Main Menu), select “Quick Test
Purge Comp.” Connect a pressure gage to purge compressor
inlet Schrader valve (suction is top fitting). The purge system
is shown in Fig. 18.The reading should be about 0 to 0.5 psig
(0 to 3.5 kPa). If not, please adjust the purge expansion valve
in the R-134a purge compressor circuit until the reading is
correct.
NOTE: This step should only be performed if the purge is not
working correctly. The installation of the gage will result in a
loss of refrigerant and the charge of R-134a is a very small
quantity affecting the operation of the purge. The charge
should be weighed into this circuit using a charging cylinder or
similar device.
Fig. 18 — Purge System
CAUTION
Disconnect leads to VFD prior to megohm test. The voltage
generated from the tester can damage VFD components.
SUCTION
SCHRADER
VALVE
NOTE: CLOCKWISE ROTATION OF
EXPANSION VALVE ADJUSTMENT
SCREW INCREASES THE PRESSURE
SETTING AND COUNTERCLOCKWISE
ROTATION DECREASES PRESSURE
SETTING.
EXPANSION VALVE
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