Manual 2100-665A
Page
42 of 51
Signal
Description
Possible Cause
Component to Check
Recommended Action
Device
Actions
Mixed Air
Temperature
Sensor Failed
Alarm
The alarm is activated
if the sensor is faulty, a
sensor wire is loose or
an out-of-range value
is read.
The alarm is activated
if the sensor is faulty, a
sensor wire is loose or
an out-of-range value
is read.
Check the mixed air
temperature sensor
wiring.
Check temperature
vs. resistance of
temperature sensor.
Replace the supply
air temperature
sensor.
Outdoor
Temperature
Sensor Failed
Alarm
The alarm is activated
if the sensor is faulty, a
sensor wire is loose or
an out-of-range value
is read.
The alarm is activated
if the sensor is faulty, a
sensor wire is loose or
an out-of-range value
is read.
Check the outdoor
temperature sensor
wiring.
Check temperature
vs. resistance of
temperature sensor.
Replace the outdoor
temperature sensor.
Outdoor
Humidity Sensor
Failed Alarm
The alarm is activated
if the sensor is faulty, a
sensor wire is loose or
an out-of-range value
is read.
The alarm is activated
if the sensor is faulty, a
sensor wire is loose or
an out-of-range value
is read.
Check the humidity
sensor wiring.
Replace the humidity
sensor.
Return Air
Temperature
Sensor Failed
Alarm
The alarm is activated
if the sensor is faulty, a
sensor wire is loose or
an out-of-range value
is read.
The alarm is activated
if the sensor is faulty, a
sensor wire is loose or
an out-of-range value
is read.
Check the return air
temperature sensor
wiring.
Check temperature
vs. resistance of
temperature sensor.
Replace the return air
temperature sensor.
High Mixed Air
Temperature
Alarm
During economizer
operation, MAT was
above alarm setpoint.
Bringing in warm air
from outside.
Damper
Verify damper
operation.
OAT sensor
Verify sensor
operation.
Low Mixed Air
Temperature
Alarm
During economizer
operation, MAT was
below alarm setpoint.
Bringing in cool air
from outside.
Damper
Verify damper
operation.
OAT sensor
Verify sensor
operation.
Damper Open
Fail Alarm
Alarm is reset
automatically.
Free cooling damper
fails to open.
Check the damper
linkage. Check to see
if anything is in the
way of the damper.
Indoor Blower:
On
Damper: Off
Damper Close
Fail Alarm
Alarm is reset
automatically.
Free cooling damper
fails to close.
Check the damper
linkage. Check to see
if anything is in the
way of the damper.
Indoor Blower:
On
Damper: Off
Smoke Alarm
Smoke detector input
signals smoke event.
Smoke sensor fail.
Smoke detector
Replace smoke
detector
Unit disabled
TROUBLESHOOTING MULTI-TEC WALL-MOUNT UNIT ALARMS (CONT.)