Service Manual

17
The bearings are permanently lubricated; therefore, no oil
ports are provided.
For suspected electrical failures, check for loose or faulty
electrical connections, or defective fan motor capacitor. The
fan motor is equipped with a thermal overload device in the
motor windings which may open under adverse operating
conditions. Allow time for the motor to cool so the device
can reset. Further checking of the motor can be done with
an ohmmeter. Set the scale on R X 1 position, and check for
continuity between 3 leads. Replace motors that show an
open circuit in any of the windings. Place 1 lead of the
ohmmeter on each motor lead. At the same time, place the
other ohmmeter lead on the motor case (ground). Replace
any motor that shows resistance to ground, arcing, burning,
or overheating.
Compressor Plug
The compressor electrical plug provides a quick- tight
connection to compressor terminals. The plug completely
covers the compressor terminals and the mating female
terminals are completely encapsulated in plug. Therefore,
terminals are isolated from any moisture so corrosion and
resultant pitted or discolored terminals are reduced. The
plug is oriented to relief slot in terminal box so cover cannot
be secured if wires are not positioned in slot, assuring
correct electrical connection at the compressor. The plug
can be removed by simultaneously pulling while “rocking“
plug. However, these plugs can be used only on specific
compressors. The configuration around the fusite terminals
is outlined on the terminal covers. The slot through which
wires of plug are routed is oriented on the bottom and
slightly to the left. The correct plug can be connected easily
to compressor terminals and plug wires can easily be routed
through slot terminal cover.
It is strongly recommended to replace the compressor plug
should a compressor fail due to a suspected electrical
failure. At a minimum, inspect plug for proper connection
and good condition on any compressor replacement.
Low- Voltage Terminals
The low- voltage terminal designations, and their description
and function, are used on all split- system condensers.
W—Energizes first- stage supplemental heat through
defrost relay (wht).
R—Energizes 24- v power from transformer (red).
Y—Energizes contactor for first- stage cooling or first- stage
heating for heat pumps (yel).
O—Energizes reversing valve on heat pumps (orn).
C—Common side of transformer (blk).
COPELAND SCROLL COMPRESSOR
Scroll Gas Flow
Compression in the scroll is
created by the interaction of
an orbiting spiral and a
stationary spiral. Gas enters
an outer opening as one of the
spirals orbits.
The open passage is sealed off
as gas is drawn into the spiral.
By the time the gas arrives at
the center port, discharge
pressure has been reached.
Actually, during operation, all
six gas passages are in various
stages of compression at all
times, resulting in nearly con-
tinuous suction and discharge.
As the spiral continues to orbit,
the gas is compressed into an
increasingly smaller pocket.
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A90198
Fig. 11 – Scroll Compressor Refrigerant Flow
The compressors used in these products are specifically
designed to operate with designated refrigerant and cannot
be interchanged. The compressor is an electrical (as well as
mechanical) device. Exercise extreme caution when
working near compressors. Power should be shut off, if
possible, for most troubleshooting techniques. Refrigerants
present additional safety hazards.
PERSONAL INJURY HAZARD
Failure to follow this caution may result in personal
injury.
Wear safety glasses, protective clothing, and gloves
when handling refrigerant.
CAUTION
!
The scroll compressor pumps refrigerant through the
system by the interaction of a stationary and an orbiting
scroll. (See Fig. 11.) The scroll compressor has no dynamic
suction or discharge valves, and it is more tolerant of
stresses caused by debris, liquid slugging, and flooded
starts. The compressor is equipped with an internal
pressure relief port. The pressure relief port is a safety
device, designed to protect against extreme high pressure.
The relief port has an operating range between 550 to 625
psi differential pressure for R- 410A and 350 to 450 psi
differential pressure for R- 22. Scrolls have a variety of shut
down solutions, depending on model, to prevent backward
rotation and eliminate the need for cycle protection.