2
ST 5110
QM 1329.rev.00
CAUSE
SOLUTION
PROBLEM
The display
shows sudden
variations in the
room or outside
temperature.
A variation in
resistance is
induced on a
probe.
Be sure the probes are dry.
Locate them away from drafts
and sources of radiant heat-
ing.
Be sure the outside probe is
installed correctly. Refer to
"Installing the outside probe"
There is electrical
noise near a probe
cable.
Isolate the 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°.
The stage 1
variable speed
cooling fans are
not running.
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
COMMON is supplied by line L1.
The wiring is
incorrect.
Correct the problem and
replace the fuse.
The stage 1 fuse is
open.
The display board
interconnect cable is
not properly plugged
into the power supply
board.
Be sure the cable is firmly
plugged in.
