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PROBLEM
The stage 1 or
stage 2 variable
speed fans run
erratically.
The stage 1
variable speed
fans run
continuously
when the room
temperature is
below the room
set point.
46
TC4-2N6F.rev.07
CAUSE
The selected motor
curve is inappropri-
ate.
The band width or
differential is too
small.
The stage 1 time on
or time off is too
short.
A variation in
resistance induced
on a room probe
causes this probe to
measure sudden
variations in the
room temperature.
Electrical noise near
a room probe cable
causes this probe to
measure sudden
variations in the
room temperature.
The stage 1 time off
is set to zero.
The wiring is
incorrect.
SOLUTION
Select an appropriate motor
curve. Refer to "Motor Curves"
Adjust the band width or
differential to a higher value.
Adjust the stage 1 time on or
time off to a higher value.
Be sure the room probes are
dry. Locate them away from
drafts and sources of radiant
heating.
Isolate the room probe cables
from all high voltage sources.
Do not route probe cables and
other power cables through the
same electrical knockout. Do
not run probe cables next to
other power cables. When
crossing other power cables,
cross at 90°.
Set the stage 1 time off to
a value other than zero.
Correct the wiring. Be sure
two different lines are connected
to each fan motor: line L1
modulated by the controller
should be combined with
another line (N for 115V or L2
for 230V) to activate the motor.
Also, be sure the stage 1 and 2
COMMON is supplied by line L1.
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