Daikin VRV IV+ Service Manual page 134

4 Third party components
a
a Liquid stop valve
b Gas stop valve
2 Check if the stop valves are completely open.
The refrigerant circuit stop
valves are open?
Yes
No
To check if the refrigerant circuit is clogged
Prerequisite: Stop the unit operation (via the user interface, central
controller, operation switch, ...).
Prerequisite: Turn OFF the respective circuit breaker.
1 Wait for the refrigerant to reach the outdoor temperature.
2 Connect a manometer to the high pressure and low pressure
service ports.
3 Turn ON the power of the unit.
4 Activate Heating operation via the Cool/Heat master user
interface.
5 Read the pressure on the high and low pressure gauges. If the
difference between high and low pressure >0.2 MPa, the
refrigerant circuit might be clogged.
6 Using a thermometer, check for a temperature drop of minimum
4°C. The obstruction is most likely located where this immediate
temperature drop occurs.
Temperature drop found?
Yes
No
To check if the refrigerant circuit is correctly
charged
Due to the relationship to pressure control and electronic expansion
valve control, the amount of refrigerant needs to be examined
according to operating conditions.
Refer to the procedures shown below for correct examination.
Service manual
134
https://daikin-p.ru/catalog/vrv-daikn/naruzhnye-vrv-bloki-daikin
b
Action
Return to the troubleshooting of
the specific error and continue
with the next procedure.
Open the stop valves of the
refrigerant circuit, see
"4.2.2 Repair procedures" on
page 136.
Action
Replace the clogged part, see
"4.2.2 Repair procedures" on
page 136.
Return to the troubleshooting of
the specific error and continue
with the next procedure.
Refrigerant overcharge diagnosis
1 High pressure rises. Consequently, overload control is
conducted to cause insufficient cooling capacity.
2 The superheated degree of suction gas lowers (or the wet
operation is performed).
becomes lower in discharge pipe temperature despite of
pressure loads.
3 The subcooling degree of condensate rises. Consequently, in
heating, the temperature of discharge air through the subcooled
section becomes lower.
Cooling
High pressure drooping control
High pressure gradually rises with
increasing operating frequency.
High
pressure
(Low pressure is maintained
Low
at a certain level.)
pressure
Operating
frequency
To maintain low pressure, operating
frequency increases on the capacity control.
(Degree of overcharge)
Proper amount
Heating
The outdoor unit electronic expansion valve
is closed due to the overload control.
Frequency comes to
the minimum level.
(High pressure is
High
maintained at a
pressure
constant level.)
Low
pressure
Low pressure rises
due to decreased
frequency.
Frequency
To maintain high pressure, frequency
decreases under the capacity control.
(Degree of overcharge)
Proper amount
Refrigerant shortage diagnosis
4 The superheated degree of suction gas rises. Consequently,
the compressor discharge gas temperature becomes higher.
5 The superheated degree of suction gas rises. Consequently,
the electronic expansion valve turns open.
6 Low pressure drops to cause the unit not to demonstrate
cooling capacity (or heating capacity).
Cooling
Consequently, the compressor
Operating frequency comes to
the lowest level.
Subcooling degree becomes
higher. (The temperature of
liquid connection piping
becomes lower.)
Low pressure rises with lowering
compressor output.
Further overcharge
High pressure drops or rises
immediately after the
overload control is complete.
Low pressure drops due to
closed outdoor unit
electronic expansion valve.
Hot gas bypass is activated
for low pressure protection,
i.e., hunting at low pressure.
Higher degree of
overcharge
RYYQ+RYMQ+RXYQ8~20U7Y1B
VRV IV+ Heat Pump
ESIE18-14 – 2019.07