AE4-1312 R2
© 2010 Emerson Climate Technologies
Printed in the U.S.A.
7
semi-hermetic compressors which can have horizontal
motors partially submerged in oil and refrigerant. When
Copeland Scroll compressors are Hipot tested with liquid
refrigerant in the shell, they can show higher levels of
leakage current than compressors with the motor on top.
This phenomenon can occur with any compressor when
the motor is immersed in refrigerant. The level of current
leakage does not present any safety issue. To lower the
current leakage reading, the system should be operated
for a brief period of time to redistribute the refrigerant
to a more normal configuration and the system Hipot
tested again. See AE Bulletin 4-1294 for Megohm testing
recommendations. Under no circumstances should the
Hipot test be performed while the compressor is under
a vacuum.
Final Run Test
Single phase scrolls with an electrical characteristic of
“
PFV
” (208-230 volt, 1Ô, 60 Hertz) at the end of the
model number may not be started at a voltage lower
than 187 volts and must have a voltage no lower than
197 volts once the compressor is running under load.
Variable transformers used on assembly lines are often
not capable of starting larger compressors at a particular
voltage setting. To test for voltage sag during the initial
locked rotor starting phase the first compressor in a
production run should be used to preset the voltage.
Remove the start wire from the compressor and apply
200 volts to the compressor. With the start winding
removed the compressor will remain in locked rotor long
enough to read the voltage supply. If the voltage sags
below the minimum guaranteed starting voltage the
variable transformer must be preset to a higher voltage
to start the compressor at a higher voltage.
Other compressor voltages
. All other compressor
voltages, both single and three phase are guaranteed
to start and run at 10% below the lowest voltage shown
on the nameplate.
Unbrazing System Components
Caution! Before opening a system it is important
to remove all refrigerant from both the high and
low side.
If the refrigerant charge is removed from a
scroll-equipped unit by bleeding one side only, it is very
possible that either the high or low side of the system
remains pressurized. If a brazing torch is then used
to disconnect tubing, the pressurized refrigerant and
oil mixture could ignite when it escapes and contacts
the brazing flame.
It is important to
check both the
high pressure and low pressure side
with manifold
gauges before unbrazing.
Instructions should be
provided in appropriate product literature and assembly
(line repair) areas. If compressor removal is required,
the compressor should be cut out of system rather
than unbrazed. See
Figure 6
for proper compressor
removal procedure.
Copeland Scroll Functional Check
A functional compressor test during which the suction
service valve is closed to check how low the compressor
will pull suction pressure is not a good indication of
how well a compressor is performing.
Such a test will
damage a scroll compressor.
The following diagnostic
procedure should be used to evaluate whether a
Copeland Scroll compressor is functioning properly:
1. Proper voltage to the unit should be verified.
Determine if the internal motor overload protector
has opened or if an internal motor short or ground
fault has developed. If the protector has opened,
the compressor must be allowed to cool sufficiently
to allow it to reset.
2. Check that the compressor is correctly wired.
3. Proper indoor and outdoor fan/blower operation
should be verified.
4. With service gauges connected to suction and
discharge pressure fittings, turn on the compressor.
If suction pressure falls below normal levels the
system is either low on charge or there is a flow
blockage in the system.
5. Single Phase Compressors
If the compressor starts and the suction pressure
does not drop and discharge pressure does not rise
to normal levels, either the reversing valve (if so
equipped) or the compressor is faulty. Use normal
diagnostic procedures to check operation of the
reversing valve.
Three Phase Compressors
If suction pressure does not drop and discharge
pressure does not rise to normal levels, reverse
any two of the compressor power leads and reapply
power to make sure the compressor was not wired
to run in reverse. If pressures still do not move
to normal values, either the reversing valve (if so
equipped) or the compressor is faulty. Reconnect
the compressor leads as originally configured
and use normal diagnostic procedures to check
operation of the reversing valve.
6. To test if the compressor is pumping properly, the
compressor current draw must be compared to
published compressor performance curves using
the operating pressures and voltage of the system.
If the measured average current deviates more than
±15% from published values, a faulty compressor
may be indicated. A current imbalance exceeding
