Page 7
Revised 05−2009
TPA*S4
1
2
3
4
SUCTION
SUCTION
ORBITING SCROLL
STATIONARY SCROLL
SUCTION
SUCTION
DISCHARGE
SUCTION
INTERMEDIATE PRESSURE
GAS
CRESCENT
SHAPED
GAS POCKET
HIGH PRESSURE GAS
FLANKS SEALED
BY CENTRIFUGAL
FORCE
MOVEMENT OF ORBIT
FIGURE 8
Make sure all power is disconnected before
beginning electrical service procedures.
DANGER
C − Outdoor Fan Motor B4
All units use single−phase PSC fan motors . In all units, the
condenser fan is controlled by the compressor
contactor (and defrost control during defrost cycles).
ELECTRICAL DATA tables in this manual show
specifications for condenser fans used in TPA*S4s.
Access to the condenser fan motor on all units is gained
by removing the seven screws securing the fan
assembly. See figure 9. The outdoor fan motor is
removed from the fan guard by removing the four nuts
found on the top panel. If outdoor fan motor must be
replaced, align fan hub flush with motor shaft. Drip loops
should be used in wiring when servicing motor.
FAN
CONDENSER FAN MOTOR
AND COMPRESSOR ACCESS
Remove (7) screws
REMOVE (7) SCREWS
SECURING FAN GUARD.
REMOVE FAN GUARD/FAN
ASSEMBLY.
FAN GUARD
WIRING
FIGURE 9
Remove (4) nuts
ALIGN FAN HUB
FLUSH WITH
MOTOR SHAFT
D − Reversing Valve L1 and Solenoid
A refrigerant reversing valve with electro−mechanical
solenoid is used to reverse refrigerant flow during unit
operation. The reversing valve requires no maintenance.
The only replaceable part is the solenoid. If the reversing
valve itself has failed, it must be replaced.
If replacement is necessary, access reversing valve by
removing the outdoor fan motor. Refer to figure 9.
E − Crankcase Heater HR1 and Optional
Thermostat S40
Crankcase heater HR1 prevents liquid from accumulating
in the compressor. HR1 is controlled by crankcase heater
thermostat S40, located on the liquid line. When liquid line
temperature drops below 50° F, S40 closes energizing
HR1. S40 opens when liquid line temperature reaches 70°.
F − High Pressure Switch S4
S4 is a manual re−set switch located on the liquid line.
When liquid line pressure rises above the factory setting of
590 + 10 psi, the switch opens and shuts off the
compressor.
G − Low Pressure Switch S87
S87 is an auto−reset low pressure switch located on the
suction line. The switch shuts of the compressor when
suction pressure drops below the factory setting. The
switch is ignored during the first 90 seconds of compressor
start up, during defrost operation,90 seconds after defrost
operation and during test mode. The switch is factory set to
open at 25 + 5 psig and close at 40 + 5 psig. These settings
are not adjustable.
