SERVICING
23
INDOOR UNIT TROUBLESHOOTING
AUXILIARY ALARM SWITCH
The control is equipped with two Auxiliary Alarm terminals,
labeled TB4 and TB5, which are typically utilized in series
with a condensate switch but could also be used with com-
patible CO2 sensors or fire alarms.
The auxiliary alarm switch must be normally closed and
open when the alarm occurs. For example, a normally
closed condensate switch will open when the base pan’s
water level reaches a particular level. The control will
respond by turning off the blower motor and displaying the
proper fault codes. If the switch is later detected closed
for 30 seconds, normal operation resumes and the error
message is removed. The switch is closed as part of the
default factory setting. The error will be maintained in the
equipment’s fault history.
CIRCULATOR BLOWER
This air handler is equipped with a variable speed circulator
blower. This blower provides several automatically-adjusted
blower speeds. The Specification Sheet applicable to your
model provides an airflow table, showing the relationship
between airflow (CFM) and external static pressure (E.S.P.).
NOTE: Upon start up in communicating mode the circuit
board may display an “Ed” error. This is an indication that
the dip switches on the control board need to be configured
in accordance with the Electric Heating Airflow Table. Con
-
figuring the dip switches and resetting power to the unit will
clear the error code.
X3A
X15A
X5A
SEG2
SEG1
X12A
X13A
X8A
INDOOR UNIT PCB
THERMISTOR
Micro
Processor
PRESSURE SENSOR
EEV
COIL
FUSE
TB4
TB1
TB5
TB2
C
R
2
1
S1
S2
S3
S4
H
ea
te
rK
it
O
ut
pu
t
EC
M
M
ot
or
O
N
O
FF
D
S1
D
S2
D
S3
D
S
4
D
S
5
FU
S
E
F1
U
X1
A
SH
A
RE
D
A
TA
S5
S6
S7
S8
S9
S1
0
S1
1
S1
2
S1
3
S1
4
S1
5
S1
6
S1
7
S1
8
S1
9
S2
0
S2
1
S2
2
F2
U
TB
6
TB
8
TB
7
TB
10
TB
3
D
S
6
O
N
O
FF
7seg
7seg
X2
A
X7
A
C
R
2
1
AUXALARM
C
R
2
1
ACC-OUT
ACC-IN
(Accessory)
(Accessory)
B
S
2
B
S
1
FA
U
LT
R
E
C
A
LL
LE
A
R
N
RX LED
CPU LED
STATUS LED
HIGH VOLTAGE !
D
ISCONNECT
ALL
POWER
BEFORE
SERVICING
.
M
ULTIPLE
POWER
SOURCES
MAY
BE
PRESENT
. F
AILURE
TO
DO
SO
MAY
CAUSE
PROPERTY
DAMAGE
,
PERSONAL
INJURY
OR
DEATH
.
WARNING
