ULT Energy-saving Series
After-sales Service Manual
46
12.2 Troubleshooting of common problems
Problem
Cause analysis
Maintenance measures
1. High
temperature
stage
compressor does
not start
1. Power switch or fuse fault
Measure the resistance of the switch or fuse with a
multimeter, if it is confirmed that the switch is broken,
replace the fuse or power switch.
2. The connector for machine
compartment is damaged.
Check whether the socket of machine compartment
connecting wire is damaged or the harness is dropped, and
replace the corresponding patch cord.
3. Poor wire contact
Check whether the patch cord is poorly connected or not
connected, and repair it until the connection is normal.
4. Wiring fault of display board
and control board
Measure the resistance of the connecting wire with a
multimeter to determine the harness short circuit or open
circuit fault, and then replace the harness if it is unable to
be repaired.
5. Relay, starting capacitor or
thermal protector is out of order
Check the relay, capacitor or thermal protector for signs of
burned black or scorched of electrical parts, and replace
the electrical parts if it is the case.
6. Compressor fault
In other cases with normal power on, check whether the
connection plug of the compressor is normal, and observe
the surface temperature and the abnormal noise, etc. of the
compressor at the same time. If the compressor is not hot
or the noise is abnormal, the compressor is out of order, so
replace the compressor; when replacing the compressor,
the oil separator and dry filter should be replaced as well.
7. Too low voltage of the user
Check whether the voltage on the display board of the
product is within the rated range (220±10%). At the same
time, use a multimeter to measure whether the voltage is
overvoltage under the condition of power on. If the voltage
is too low or too high, the customer is required to provide
a voltage regulator.
2. Low
temperature
stage
compressor does
not start
1. Same as the causes of not
starting
of
high
temperature
compressor
In other cases with normal power on, check whether the
connection plug of the compressor is normal, and observe
the surface temperature and the abnormal noise, etc. of the
compressor at the same time. If the compressor is not hot
or the noise is abnormal, the compressor is out of order, so
replace the compressor; when replacing the compressor,
the oil separator and dry filter should be replaced as well.
2. Pressure switch is out of order
Measure the harness of pressure switch with a multimeter
for short circuit and open circuit, and at the same time,
check whether the copper pipe of pressure switch is
damaged, and replace the pressure switch in case of fault.
3. Poor refrigeration of high
temperature stage system
If the low temperature compressor does not start after 10
min of the startup of high temperature stage system, it
indicates poor refrigeration of high temperature stage
system. Check whether the circuit and pipeline welding of
high temperature stage system is good (if any blockage
and leakage), and deal with the fault.
3. The fan does
not work
1. The fan is dropped
Check whether the fan connector wire is dropped or not,
and reprocess the wire head and butt installation
2. Fan blade are blocked by foreign
matters
Check whether there is wall collision noise or not in the
rotation of fan blades, treat the blades and surrounding
foreign matters, and keep the blades running normally.
3. The fan is out of order
Measure the resistance at both ends of the fan wiring with
a multmeter and check for short circuit or open circuit, and
observe whether the rotation shaft rotates at the same time.
If as the cases above, please replace the fan.
4. High
1. High setting temperature of Check whether the setting temperature of the product is set
