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Defrost
The defrost control mode is a time/temperature sequence. There
are two time components: The continuous run period and the test/
defrost cycle period. The temperature component is provided by
Defrost Thermostat 1 and 2 (DFT1 and DFT2) mounted on the
outdoor coil.
The continuous run period is a fixed time period between the end
of the last defrost cycle (or start of the current Heating cycle)
during which no defrost will be permitted. This period can be set
at 30, 60, 90 or 120 minutes by changing the positions of DIP
switches SW1 and SW2 (see Fig. 37 and Table 7). The default run
period is 60 minutes for size 12 units.
Shorting the jumpers for a period of 5 to 20 seconds bypasses the
remaining continuous run period and places the unit in a Forced
Defrost mode. If the controlling DFT is closed when this mode is
initiated, the unit will complete a normal defrost period that will
terminate when the controlling DFT opens or the 10 minute de-
frost cycle limit is reached. If the controlling DFT is open when
this mode is initiated, the Defrost cycle will run for 30 seconds.
Both modes end at the end of the Defrost cycle.
Fig. 37 — DIP Switch Settings - Defrost Board
UNIT WITHOUT THRU-BASE CONNECTION KIT
Pass the thermostat control wires through the bushing on the unit
end panel. Route the wire through the snap-in wire tie and up to
the web bushing near the control box. Route the wire through the
bushing and into the bottom left side of the control box after re-
moving one of the two knockouts in the corner of the box. Using a
connector at the control box to protect the wire as it passes into the
control box. Pull the wires over to the terminal strip at the upper
left corner of the Central Terminal Board (CTB). Use the connec-
tor at the control box and the wire tie to ensure that the thermostat
wire is tight and will not be damaged by contact with the condens-
er coil. See Fig. 38.
NOTE: If thru-the-bottom connections accessory is used, refer to
the accessory installation instructions for information on routing
power and control wiring.
Fig. 38 — Thermostat Wire Routing
HEAT ANTICIPATOR SETTINGS
Set heat anticipator settings at 0.14 amp for the first stage and 0.14
amp for second-stage heating, when available.
ELECTRIC HEATERS
50HCQ units may be equipped with field-installed accessory elec-
tric heaters. The heaters are modular in design, with heater frames
holding open coil resistance wires strung through ceramic insula-
tors, line-break limit switches and a control contactor. One or two
heater modules may be used in a unit.
Heater modules are installed in the compartment below the indoor
(supply) fan outlet. Access is through the indoor access panel.
Heater modules slide into the compartment on tracks along the
bottom of the heater opening. See Fig. 39.
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment damage.
Not all available heater modules and single point boxes may
be used in every unit. Use only those heater modules that are
UL listed for use in a specific size unit. Refer to the label on
the unit cabinet for the list of approved heaters and single point
boxes.
22
CAUTION
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