95
Part 4 - Diagnosis and T
roubleshooting
4.19.4 Procedure
PE
Taf temperature sensor connection on
main PCB is loose
1
Taf temperature sensor has
short-circuited or failed
2
Insufficient refrigerant caused by
refrigerant leakage
3
The low pressure side is blocked, caused
by crushed or bent pipe, blocked EXV, or
dirty filter
4
The air side heat exchanger heat
exchange is poor in heating mode
5
The water flow rate is not sufficient in
cooling mode
6
Replace main PCB
No
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Ensure the sensor is connected properly
Replace the sensor
Add refrigerant or inspect the system for
leaks
Inspect the system and fix the error. If the
filter is blocked by ice, the piping should
be cleaned
Inspect the refrigerant system and fix the
error
Inspect the water system and fix the
error
Notes:
1. For 30kW and 60kW units, water side heat exchanger anti-freezing temperature sensor (Taf, include Taf1 and Taf2) connection are ports CN69 and CN31 on
the main PCB (labeled 4 and 8 in in Figure 4-2.1 in Part 4, 2.2 “Main PCB”).
2. Measure sensor resistance. If the resistance is too low, the sensor has short-circuited. If the resistance is not consistent with the sensor’s resistance
characteristics table, the sensor has failed. Refer Table 5-5.3 in Part 5, 5.1 “Temperature Sensor Resistance Characteristics”.
3. To check for insufficient refrigerant: an insufficiency of refrigerant causes compressor discharge temperature to be higher than normal, discharge and
suction pressures to be lower than normal and compressor current to be lower than normal, and may cause frosting to occur on the suction pipe. These
issues disappear once sufficient refrigerant has been charged into the system.
4. A low pressure side blockage causes compressor discharge temperature to be higher than normal, suction pressure to be lower than normal and
compressor current to be lower than normal, and may cause frosting to occur on the suction pipe. For normal system parameters.
5. Check air side heat exchanger, fan(s) and air outlets for dirt/blockages.
6. Check water side heat exchanger, water piping, circulator pumps and water flow switch for dirt/blockages.
