Mitsubishi Electric PUHY-P200 Service Handbook page 139

(4) In the case of 21S4b (4-way switching valve)
About this 4-way valve
When not powered : The electricity runs between the oil separator exit and the heat exchanger (in the case of
P400 types) HEXB, between heat exchangers at the rear (in the case of P450-P650 types),
and between HEX1b and 2b (heat exchanger on the left (as you face the front of the unit)).
When powered : The electricity runs between the heat exchanger and the accumulator, and the valve opens
or closes the heat exchanger circuit when cooling or heating.
Check the LED display and the switching sound to check whether the valve has no faults, however, it may be oc-
casionally difficult to check by the sound, as the switching coincides with 21S4a and 21S4c. In this case, check
the intake and the discharge temperature for the 4-way valve to check that the electricity runs between where
and where.
✻1 Do not touch the valve when checking the temperature, as it will be hot.
✻2 Do not give an impact from outside, as the outer hull will be deformed leading to the malfunction of the inner valve.
(5) In the case of 21S4c (4-way switching valve) (Only P400-P650 types)
About this 4-way valve
When not powered : The electricity runs between the oil separator exit and the heat exchanger (in the case of
P400 types) HEXF, between heat exchangers at the front (in the case of P450-P650 types)
HEX1a, and between the heat exchangers on the right (as you face the front of the unit).
When powered : The electricity runs between the heat exchanger and the accumulator, and the valve opens
or closes the heat exchanger circuit when cooling or heating.
Check the LED display and the switching sound to check whether the valve has no faults, however, it may be oc-
casionally difficult to check by the sound, as the switching coincides with 21S4a and 21S4c. In this case, check
the intake and the discharge temperature for the 4-way valve to check that the electricity runs between where
and where.
✻1 Do not touch the valve when checking the temperature, as it will be hot.
✻2 Do not give an impact from outside, as the outer hull will be deformed leading to the malfunction of the inner valve.
(6) In the case of SV5b (2-way switching valve)
This valve closes when powered. Check the LED display and the switching sound to check whether the valve has
no faults. When cooling, the switching coincides with 21S4b. When it is difficult to check by the sound, check the
temperature at the front and the back of the pipe to check whether the refrigerant flows.
✻
Do not give an impact from outside, as the outer hull will be deformed leading to the malfunction of the inner valve.
(7) In the case of SV5c (2-way switching valve) (Only P400-P650 types)
This valve closes when powered. Check the LED display and the switching sound to check whether the valve has
no faults. When cooling, the switching coincides with 21S4c. When it is difficult to check by the sound, check the
temperature at the front and the back of the pipe to check whether the refrigerant flows.
✻
Do not give an impact from outside, as the outer hull will be deformed leading to the malfunction of the inner valve.
4. Outdoor unit fan
• To check the revolution of the fan, check the inverter output state on the LED screen, as the inverter on the out-
door fan controls the revolutions of the fan. The revolution of the fan is approximately 600rpm at full speed.
• When starting the fan, the fan runs at full speed for 5 seconds.
• For the 2 fans for P450-P650 types, the fan on the right (as you face the fan) runs at all times and the fan on the
left runs when required. (When heating except for defrost, both fans run.)
• When setting the DIP SW1 to
speed and 0% indicates the stop.
• As the revolution of the fan changes under control, at the interphase or when the indoor unit operation capacity is
low, the revolution of the fan may change.
• When the fan does not work or an abnormal vibration occurs, the FAN board is defective, or the fan motor runs
under open phase or opposite phase. (The microcomputer detects the open phase or the opposite phase of the
main power source, however, these malfunctions may occur when doing other service work or when the lead wire
for the fan motor is intentionally replaced.)
• When the only one fan is running and the other fans are stopped, check the 52F output state on the LED screen
first and check the fan connector and 52F connector misconnection, 52F failure, or the lead wire disconnection.
1 2 3 4 5 6 7 8 9 10
ON
, the inverter output [%] will appear. 100% indicates the full
- 137 -