Daikin VRV IV+ Service Manual page 78

3 Components
RYYQ-U units:
▪ Cooling mode
▪ Oil return operation in cooling mode
RYMQ-U units:
▪ Cooling mode
▪ Oil return operation in cooling mode
14 With the 4‑way valve connector connected to the PCB,
measure the voltage on the 4‑way valve connection of the PCB.
Result: The measured voltage MUST be 0 V AC.
Is the measured voltage
correct?
Yes
No
To perform a position check of the 4-way valve
1 First perform an electrical check of the 4‑way valve, see
"Checking procedures" on page 77.
When outdoor temperature is mild and unit can switch between
heating and cooling
INFORMATION
This procedure is ONLY possible when the outdoor
temperature is within the temperature range for both
Heating and Cooling operation mode. See the databook
on Business Portal for the temperature range of the
operation modes.
2 Activate Heating operation via the Cool/Heat master user
interface.
CAUTION
It is NOT possible to activate operation modes with another
user interface than the Cool/Heat master user interface.
INFORMATION
It is recommended to connect the service monitoring tool to
the unit and verify the operation mode of the 4-way valve.
3 Check with a contact thermometer (or by touching) if the flow
through the 4-way valve corresponds with the flow shown in the
flow diagram. (See "6.3 Piping diagram" on
Is the flow correct?
Yes
No
4 Connect a manifold to one of the service ports of the refrigerant
circuit and check the pressure (suction, discharge). Compare
with normal operation conditions of the unit.
Refrigerant pressure correct?
Yes
No
5 De-activate Heating and activate Cooling operation via the
Cool/Heat master user interface.
Service manual
78
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Action
Perform a position check of the
4-way valve, see "Checking
procedures" on page 77.
Perform a check the main PCB,
see "3.9 Main PCB" on
page 106.
page 148).
Action
Skip the next step of this
procedure.
Perform the next step of this
procedure.
Action
Replace the body of the 4‑way
valve, see "Repair
procedures" on page 78.
Leaks may be found in the
refrigerant circuit. Perform a
pressure test of the refrigerant
circuit, see "4.2.1 Checking
procedures" on page 133.
6 Check with a contact thermometer (or by touching) if the flow
through the 4-way valve corresponds with the flow shown in the
flow diagram. (See "6.3 Piping diagram" on
Is the flow correct?
Yes
No
When outdoor temperature does not allow the unit to run in
cooling or heating mode
INFORMATION
Follow this procedure when the outdoor temperature is
outside the temperature range for one of the operation
modes (Heating or Cooling). The unit CANNOT operate
in the mode for which the outdoor temperature is outside
its temperature range. See the databook on Business
Portal for the temperature range of the operation modes.
7 With the unit operating, connect the service monitoring tool to
the unit and check in which of the following operation modes
the unit is operating:
RXYQ-U units:
▪ Heating mode and oil return in heating mode
▪ Defrost operation
▪ Cooling mode
▪ Oil return operation in cooling mode
RYYQ-U and RYMQ-U units:
▪ Oil return operation and defrost operation in heating mode
▪ Heating mode
▪ Cooling mode
▪ Oil return operation in cooling mode
8 Check with a contact thermometer (or by touching) if the flow
through the 4-way valve corresponds with the flow shown in the
flow diagram of the specific operation mode. (See
diagram" on page 148).
Is the flow correct?
Yes
No
9 Connect a manifold to one of the service ports of the refrigerant
circuit and check the pressure (suction, discharge). Compare
with normal operation conditions of the unit.
Refrigerant pressure correct?
Yes
No
Repair procedures
To remove the 4-way valve coil
Prerequisite: Stop the unit operation (via the user interface, central
controller, operation switch, ...).
Prerequisite: Turn OFF the respective circuit breaker.
page 148).
Action
4‑way valve is OK. Return to the
troubleshooting of the specific
error and continue with the next
procedure.
Replace the body of the 4‑way
valve, see "Repair
procedures" on page 78.
"6.3 Piping
Action
4‑way valve is OK. Return to the
troubleshooting of the specific
error and continue with the next
procedure.
Perform the next step of this
procedure.
Action
Replace the body of the 4‑way
valve, see "Repair
procedures" on page 78.
Leaks may be found in the
refrigerant circuit. Perform a
pressure test of the refrigerant
circuit, see "4.2.1 Checking
procedures" on page 133.
RYYQ+RYMQ+RXYQ8~20U7Y1B
VRV IV+ Heat Pump
ESIE18-14 – 2019.07