Compressor Internal Relief
The compressor is protected by an internal pressure relief (IPR)
which relieves discharge gas into compressor shell when differen-
tial between suction and discharge pressures exceeds 525 psi. The
compressor is also protected by an internal overload attached to
motor windings.
Compressor Control Contactors
Low and high capacity contactor coils are 24 volts. The electronic
control board controls the operation of the low speed (C-L) and the
high speed (C-H) contactors.
TEMPERATURE THERMISTORS
Thermistors are electronic devices which sense temperature. As
the temperature increases, the resistance decreases. Thermistors
are used to sense outdoor ambient and coil temperature. Refer to
Fig. 15 for resistance values versus temperature.
If the outdoor ambient thermistor or coil thermistor should fail, a
fault code appears at electronic control. The crankcase heater is
turned on during all off cycles.
IMPORTANT:
OUTDOOR AIR THERMISTOR PLACEMENT
Mount outdoor air thermistor underneath unit base pan lip on
control box side of unit as shown in Fig. 16. Attach to base pan
with adhesive tape. A small piece of TXV bulb insulation tape may
be used.
IMPORTANT:
If outdoor air thermistor is not properly placed
underneath base pan, unit may have nuisance thermistor out of
range faults.
Step 14—Final Checks
IMPORTANT:
Before leaving job, be sure to do the following:
1. Ensure that all wiring and tubing is secure in unit before
adding panels and covers. Securely fasten all panels and
covers.
2. Tighten service valve stem caps to 1/12-turn past finger tight.
3. Leave User’s Manual with owner. Explain system operation
and periodic maintenance requirements outlined in manual.
4. Fill out Dealer Installation Checklist and place in customer
file.
CARE AND MAINTENANCE
For continuing high performance and to minimize possible equip-
ment failure, periodic maintenance must be performed on this
equipment. Frequency of maintenance may vary depending upon
geographic areas, such as coastal applications.
Table 6—Factory Defaults
FAILED COMPONENT
FUNCTION
DEFAULT
Ambient Thermistor
Defrost Initiation
Defrost is initiated based on coil
temperature and time.
One minute fan off delay in cooling
greater than or equal to 100°F
No delay function
Outdoor Coil Thermistor
Defrost Initiation and Termination
Defrost occurs at each time interval, but
terminate after 5 minutes
Table 7—Two-Speed Compressor
(Winding Resistance at 70°F ± 20°)
WINDING
024
036/037
048
060
Start (S-C)
2.280
1.850
1.459
0.740
Run (R-C)
0.770
0.745
0.552
0.356
Fig. 14—Control Board
A01192
Defrost Time
Selectors
Thermostat
Low Voltage
Connector
Reserved for
Future Use
Crankcase Heater
Connection
O.D.F. Connection
To Run
Capacitor
Thermistor
Connection
High Pressure
Switch Connector
Low Pressure
Switch Connector
Low/High Speed
Contactor
Connection
Reversing V
alve
Connection
CEBD430439-03A
SS0ID
PL1
PL2
HP/AC
C
SEV
RV
S
C
HI
LO
PL3
PL4
PL5
OCT O
A
T HPS LPS
PWM2
PWM1
BRN
BLU
BLK
YEL
RED
CCH L2 ODF
VH
VC
H K 3 8 E A 0 0 1
K1
CEPL130439-01
C O M M S T A T U S
D51
D52
A B C D
0
Y2
Y1
W1
C
R
120
30
60
60
30
90
DEFROST
TIME (MIN)
R39
R44
R42
C18
C16
R36
FORCED
DEFR
OST
1
1
1
S1
R89
R91
R87
R86
R85
J1
C31
R61
R65
R38
R33
C2
R9
1 2
Fig. 15—Resistance Values Versus Temperature
A91431
0
10
20
30
40
50
60
70
80
90
0
20
40
60
80
100
120
TEMPERATURE (DEG. F)
RESISTANCE (KOHMS)
THERMISTOR CURVE
13
