AIRSYS 13E1C3 - Page 59

Page 55
Code
Signal
Description
Possible Cause
Component to Check
Recommended Action
Device Actions
Supply
Fan
Compressor/
Cond Fan
Heat
Damper
A21
Backup indoor
temperature
sensor
defective
Both units stop
working. It can be
reset automatically.
Indoor temperature
sensor (port J2-B2 on
unit 2 controller) failure.
Check if the cable is
connected or shorted.
Replace it.
A20
AND
A21
Indoor and
backup indoor
temperature
sensors are
both defective
Both units stop
working. It can be
reset automatically.
Both Indoor temperature
sensors have failed.
Check if the cable is
connected or shorted.
Replace it.
Off
Off
Off
Closed
A22
Outdoor
temperature
sensor
defective
The free cooling
damper will be
closed. It can be
reset automatically.
Temperature sensor
(port J2-B3 on unit 1
controller) failure.
Check if the cable is
connected or shorted.
Replace it.
Closed
A23
Second
compressor
run alarm
Both compressors
are running at the
same time.
Heat load at the site
exceeds single HVAC
capacity.
Check if the heat load of
cell site exceeds the
nominal heat load.
None
Check if refrigerant
quantity is low.
Check for leakages in the
refrigerant system.
A24
A25
HVAC
Damper
failure
The alarm can be
automatically reset
once the alarm is
removed.
HVAC damper is broken
or blocked or loosen
Check if the damper
actuator is broken or
loose.
If loose, tighten.
If the damper actuator is
broken, replace it.
None
None
None
None
Check if the damper is
blocked.
If the damper is blocked,
clear blockage.
A26
A27
Supply air
temp. sensor
defective
Damper will stop
working. It can be
reset automatically.
HVAC Supply air temp.
sensor failure
Check if the cable is
connected to (B1&GND)
or shorted.
Replace it.
Closed
A28
Generator run
signal
This indicates that
the generator is
running.
A29
A30
HVAC air flow
defective
The PLD will display
A29/ A30
The supply fan doesn’t
work.
The 48VDC power is
powered off or no
48VDC power input
The pressure switches
PF2 or 3 or both for
HVAC supply fan are
broken.
Check the supply fan.
If the supply fan is blocked or
broken, please remove the
object or replace the fan.
Off
Off
Off
closed
Check the 48VDC power
plant.
If the 48VDC power plant has
no power, check the power
source.
Check the 48VDC power
breaker (QF2).
If the 48VDC power breaker
is broken, please replace it.