Unique CU Series, Service Manual And Spare Parts List, Page: 66 / 108

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9. TROUBLESHOOTING GUIDE
9.1 General Troubleshooting.
Note : Check for broken wires and loose cable lugs first!
Warning : Always unplug the A/C before performing cleaning or maintenance activities.
Symptom Probable Cause Corrective Action
1
A/C fails to start. 1. Power supply to unit not
connected (LCD display is
blank).
2. Fuse Blown ( LCD display
is blank).
3. ON/SEND on R/C has not
been pressed.
4. A/C does not receive
transmitted commands.
5. Electric supply wall socket
is defective.
1. Check for proper connection of power
plugs in wall socket.
Check red LED on RST Controller
(wherever applicable):
If LED is OFF – change RST wires.
If LED is ON – check Phase voltage.
2. Reset automatic circuit breaker or
replace line fuse.
3. Press ON/SEND button on R/C.
4. Make sure that noting blocking the
R/C transmission to the A/C display.
5. Repair or replace wall socket.
2 Only indoor fan
ventilator works
although cooling or
heating is desired.
1. The selected mode is on
Fan Only, or on Cool when
heating is desired.
2. Temperature is set to a
value which is too high (in
Cool mode).
3. Faulty outdoor fan motor
or other fault that cause
compressor overload
protection to cutout.
1. Check if the R/C is on the desired
mode. If not, select the correct mode
(refer to your User Manual).
2. Observe the temperature setting on
the R/C.
3. See step 3 and/or step 4.
3
Only indoor fan
motor and
compressor
working. Outdoor
fan motor stopped. 1. In Heat mode: Head
pressure is too high.
2. In Cool mode: system runs
while evaporator Anti-Ice
routine takes place.
1. Wait up to 90 seconds. Check air
flow through indoor evaporator.
Eventually clean filter.
2. Wait up to 90 seconds until Anti-Ice
routine is completed.