Mitsubishi Electric PURY-P120Y(T)HMU-A, Service Handbook

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[
IX
Troubleshooting ]
- 276 - HWE0803A GB
(4) SV4a, 4b and 4d (P72 model), SV4a - 4d (P96 and P120 models)(Controls heat exchanger capacity)
1) Depending on the conditions during Cooling-only operation, at least one of the solenoid valves among SV4a through 4d turns
on. Check for proper operation on the LED and by listening for the operation sound of the solenoid valve.
2) During Heating-only operation, SV4a through 4d all turn on. Check for proper operation on the LED and by listening for the
operation sound of the solenoid valves.
3) Depending on the conditions during Cooling-main or Heating-main operation, at least one of the solenoid valves among SV4a
through 4d turns on. Check for proper operation on the LED and by listening for the operation sound of the solenoid valve.
4) The diagram on the next page shows the refrigerant flow. This diagram shows the flow of the high-temperature (high-pressure)
gas refrigerant in the Cooling-only and Cooling-main modes and the flow of the low-temperature gas/liquid refrigerant in the
Heating-only and Heating-main modes. Refer to the refrigerant circuit diagram. Solenoid valves turns on and off according to
such factors as the capacity of the indoor units in operation and outside temperature. Check the LED. Remove the SV coil,
open the lid, and check the plunger. The type of pin face wrench that is listed in the service parts list is required to perform
this task.
ST1
CV8a
CV6a
TH7
TH3
SV4a
SV4b
SV4d
TH6
CV9a CV10a
SV5b
CV4a
CV2a
CV7a
CV3a CV5a
HEX
Solenoid Valves Block
BV1
BV2
SV5c
Refrigerant Circuit Figure (P72 model)
1
2
3
4
5
1
2
3
4
5
Solenoid valve block (three compartments) P72 model
SV4d SV4b SV4a SV4d SV4b SV4a