
10 Troubleshooting
Troubleshooting procedure
SMGB0091 rev.2 - 11/2015
203
10
Phenomenon
Cause
Check item
Action
(Turn OFF the main switch)
Activation of the
high-pressure
switch due to the
excessively high
discharge pressure
(PSH)
Insufficient air
flow to the heat
exchanger (RASC
heat exchanger
during the cooling
process or indoor
heat exchanger
during the heating
process)
Clogging of the
heat exchanger
Check if the heat exchanger
is clogged (by dust or any
strange particle)
Remove the dust or strange
particles
Check for any obstacles at the
inlet or the outlet of the heat
exchanger
Remove the obstacles
Accumulation of
dust
Check the indoor unit air filter
for dust
Remove the dust
Service space is
not respected
Check the service space have
been respected
Secure service area
Abnormally low
indoor unit fan
speed
Check the indoor fan speed
during heating operation
Replace the fan motor if faulty
Abnormally low
RASC fan speed
during cooling
mode
Check the communication line
between PCB1 and PCB3
(CN10-X1) and between PCB3
and VFD (X2-RJ45).
Connect correctly the wiring if
insufficient contact or replace it
if damaged
Check the variable frequency
driver (VFD)
Replace it if faulty
Check the fan motor
For RASC-(6/8/10)NPE units
check the optional function
“Setting of the fan performance
curves (F2)”
Select the most appropriated
setting. Refer to section
“Setting of the fan performance
in chapter
RASC fan does
not run during
cooling mode
Connect directly 400V into the
fan motor terminals and check
the fan operation
If not operation, replace the fan
motor.
Check during operation that
there are 400V between
L1,L2,L3 and between U,V,W
at the VFD
Connect correctly the wiring if
insufficient contact or replace it
if damaged
Check the communication line
between PCB1 and PCB3
(CN10-X1) and between PCB3
and VFD (X2-RJ45).
Check the variable frequency
driver during operation (VFD)
Replace the VFD in the
following cases:
- If LED PWR on VFD is OFF
- If LED RUN on VFD is OFF
- If LED ALM on VFD is ON