Installation guide

THERMISTOR CURVE
20 40 60 80 100 120
TEMPERATURE(DEG. F)
A91431
Fig. 15--Resistance Values Versus Temperature
i. De-energize the compressor hi or low speed contactor.
2. Keep the outdoor fan operating for 15 minutes.
3. Display the appropriate en'or code on the status light (see
Table 4).
4. After a 15 minute delay, if Y1 or Y2 inputs are on and the LPS
or HPS is reset, energize appropriate compressor contactor,
either low or high.
5. If LPS or HPS has not closed after 15 minute delay, outdoor
fan is turned of£ If the open switch closes anytime after the
15-minute delay, then resume operation on call for Y1 and.or
Y2.
MAJOR COMPONENTS
Two-Speed Control
The two-speed control board controls the following functions:
Low- and high-compressor contactor operation
Outdoor _an motor operation
Crankcase heater operation
Compressor protection
Pressure switch monitoring
Time delays
Time/temperature defrost
Control Box
Side of Unit
-- THERMISTOR PLACED
UNDERNEATHBASEPAN
(ATTACHED TO BASE PAN
WITH ADHESIVE)
A00430
Fig. 16--View from Top of Base Pan
Defi'ost interval selection
Electric heat operation during defrost mode
Field Connections
The two-speed control received 24vac low-voltage control system
inputs through the screw connections on the left side of the control
board.
Dual Capacity Compressor
The dual capacity compressor contains motor windings that
provide 3500 RPM operation. Refer to Table 7 for con'ect winding
resistance.
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:
i. Ensure that all wiring and tubing is secure in unit before
adding panels and covers. Securely _asten all panels and
Covers.
2. Tighten service valve stem caps to 1i12-tum 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.
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