8.3 Comfort Control
2
System™ Control Operation
A Dual Drive unit has two controls instead of a single control. A Dual Drive control is
the same as any residential communicating control. Therefore, the features such as
fault recall and the operation of the test button are the same as any JEC control.
The two controls are identical and interchangeable. This allows the controls to be
swapped for troubleshooting if one of the controls is suspected of being defective.
Only one of the controls can be connected to a communicating network. The control
that is connected to the communications network is the primary control. It is located
on the left hand side when facing the unit. The primary control puts out a 24 VAC
signal to the secondary control when second stage is called for.
Each control will have a separate history of faults (up to 6) which can be accessed
b
y pressing the “Test” and “SW2” buttons. Only the primary control fault history can
be accessed by a service tool or the thermostat.
As with any JEC unit, the airflow will be automatically optimized when the system is
used in communicating mode. If a conventional thermostat is used with the system,
the dipswitches in the air handler must be set to provide the correct airflow.
9.0 COMPRESSOR CRANKCASE HEAT (CCH)
CCH is standard on these models due to refrigerant migration during the off cycle
that can result in a noisy start up.
Crankcase Heater Operation:
Supplemental Crankcase heat is required to prevent refrigerant migration in sys-
tems with relatively high system refrigerant charges. Each Dual Drive compressor
has its own crankcase heater.
The crankcase heater control is integrated into the Comfort Control
2
System™ and
is designed for maximum energy savings.
Summary of operation:
• The crankcase heater is off whenever the compressor is running.
• Once the compressor turns off, the crankcase heater control (CCH) begins the
two-hour timer countdown.
• If the compressor stays off for two hours, the CCH turns on the crankcase heater.
All heaters are located on the lower half of the compressor shell. Its purpose is to
drive refrigerant from the compressor shell during long off cycles, thus preventing
damage to the compressor during start-up.
At initial start-up or after extended shutdown periods, make sure the heater is ener-
gized for at least 12 hours before the compressor is started. (Disconnect switch on
and wall thermostat off.)
10.0 HARD START COMPONENTS
Factory-installed start components are standard on all models.
11.0 HIGH AND LOW PRESSURE CONTROLS
10.0 (HPC AND LPC)
These controls keep the compressor from operating in pressure ranges which can
cause damage to the compressor. Both controls are in the low voltage control cir-
cuit.
High pressure control (HPC) is an automatic-reset which opens near 610 PSIG and
closes near 420 PSIG.
The low pressure control (LPC) is an automatic-reset which opens near 50 PSIG
and closes near 95 PSIG.
NOTE: HPC and LPC are monitored by the Comfort Control
2
System™. See
Section 12.0.
17
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