Service manual

PRODUCT DESIGN
12
The single phase units use permanent split capacitors (PSC)
design compressors. Starting components are therefore
not required. A low MFD run capacitor assists the com-
pressor to start and remains in the circuit during operation.
The outdoor fan and indoor blower motors are single phase
capacitor type motors.
Air for condensing (cooling cycle) or evaporation (heating
cycle) is drawn through the outdoor coil by a propeller fan,
and is discharged vertically out the top of the unit. The
outdoor coil is designed for .0 static. No additional restric-
tion (ductwork) shall be applied.
Conditioned air is drawn through the filter(s), field installed,
across the coil and back into the conditioned space by the
indoor blower.
Package Heat Pump indoor sections are designed to ac-
cept optional components such as auxiliary electric heat-
ers and circuit breakers. Provisions for these components
have been made at time of manufacture.
Some models of PGA, PGB, & PGD series package units
use the Compliant Scroll compressor, there are a number
of design characteristics which are different from the tradi-
tional reciprocating compressor.
- Due to their design Scroll compressors are inherently
more tolerant of liquid refrigerant. NOTE: Even though
the compressor section of a Scroll compressor is more
tolerant of liquid refrigerant, continued floodback or
flooded start conditions may wash oil from the bearing
surfaces causing premature bearing failure.
- These Scroll compressors use white oil which is com-
patible with 3GS. 3GS oil may be used if additional oil
is required.
- Phase 1 Scroll compressors (ZR**K1 or ZR**K2), the
compressor may run backwards (noisy operation) for 1
or 2 seconds at shutdown. This is normal and does not
harm the compressor.
- Phase 2 Scroll compressors (ZR**K3). On shutdown,
the scroll flanks will separate allowing the compressor
to equalize internally within 0.4 seconds after shutdown.
- Operating pressures and amp draws may differ from
standard reciprocating compressors. This information
may be found in the "Cooling Performance Data" sec-
tion.
The scroll is a simple compression concept first patented in
1905. A scroll is an involute spiral which, when matched
with a mating scroll form as shown (next page), generates
a series of crescent shaped gas pockets between the two
members.
During compression, one scroll remains stationary (fixed
scroll) while the other form (orbiting scroll) is allowed to
orbit (but not rotate) around the first form.
As this motion occurs, the pockets between the two forms
are slowly pushed to the center of the two scrolls while si-
multaneously being reduced in volume. When the pocket
reaches the center of the scroll form, the gas, which is now
at a high pressure, is discharged out of a port located at the
center.
During compression, several pockets are being compressed
simultaneously, resulting in a very smooth process. Both
the suction process (outer portion of the scroll members)
and the discharge process (inner portion) are continuous.
ELECTRICAL WIRING
WARNING
TO AVOID THE RISK OF ELECTRICAL SHOCK, WIR-
ING TO THE UNIT MUST BE PROPERLY POLARIZED
AND GROUNDED.
WARNING
TO AVOID ELECTRICAL SHOCK, INJURY OR DEATH,
DISCONNECT ELECTRICAL POWER BEFORE CHANG-
ING ANY ELECTRICAL WIRING.
The units are designed for operation on 60 hertz current
and at voltages as shown on the rating plate. All internal
wiring in the unit is complete. It is necessary to bring in the
power supply to the pigtails or power block, which is lo-
cated in the junction box or circuit breaker box assembly
(or compressor contactor on package gas units) , as shown
on the unit wiring diagram which is supplied with the unit.
The 24V wiring must be connected between the unit con-
trol panel and the room thermostat.
LINE VOLTAGE WIRING
Power supply to the furnace must be N.E.C. Class 1, and
must comply with all applicable codes. The furnace must
be electrically grounded in accordance with the local codes