506303-01 Page 23 of 40Issue 0938
NOTE: If a single stage thermostat is used, move the
automatic heat staging jumper pin (see Figure 33) from the
NONE position to either the 5 or 10 minute setting. Connect
rest of wiring as shown in Figure 34 or Figure 35 except in
this single stage thermostat configuration, the W2 must
remain open (only W1 should be connected).
If the red LED on the control board flashes a “9 flash” fault
code after the units are energized (see Table 5 on page 33),
switch 24V leads on the transformer in one of the units to
bring both transformers into phase.
Variable Speed Features (G2D95CT/U Models Only)
The G2D95CT/U furnace is equipped with a variable speed
circulation air blower motor that will deliver a constant airflow
within a wide range of external static pressures.
Other features of this variable speed motor include:
Soft Start
The variable speed motor will slowly ramp up to normal
operating speed. This minimizes noise and increases
comfort by eliminating the initial blasts of air encountered
with standard motors.
Continuous Blower Operation (G2D95CT/U Models)
The comfort level of the living space can be enhanced when
using this feature by allowing continuous circulation of air
between calls for cooling or heating. The circulation of air
occurs at half the full cooling airflow rate.
To engage the continuous blower operation, place the fan
switch on the thermostat into the ON position. A call for fan
from the thermostat closes R to G on the control board.
The control waits for a 1-second thermostat debounce delay
before responding to the call for fan by ramping the
circulating blower up to 50% of the cooling speed. When
the call for continuous fan is satisfied, the control
immediately ramps down the circulating blower.
Twinning (G2D93CT/U Models Only)
The integrated ignition/blower control board is designed to
permit “twinning” of furnaces (two furnaces connected to a
common supply and return air system, and controlled by
one thermostat).
When “twinning” two furnaces, each furnace must have
its own dedicated vent system.
To twin two G2D93CT/U furnaces, connect wires as shown
in either Figure 34 below or Figure 35 on page 24.
G2D95CT/U furnaces cannot be twinned.
Figure 34
Wiring Connections for Twinning Two G2D93CT/U Furnaces
Two Stage Heating/Two Stage Cooling
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