Mitsubishi Electric PUHY-200YMF-B Service Handbook page 177

Note 1 Wait until the units stabilize as described in the refrigerant amount adjustment procedure in "Chapter 6".
Note 2 After the units are operating stably, check that the refrigerant composition of αOC is within the following
ranges, indicating that the composition check is finished.
If the accumulator liquid level AL = 0 when cooling:
If the accumulator liquid level AL = 1 when cooling:
When heating:
(The self-diagnosis switch (SW1) on the main board of the outdoor unit can be used to display this data on
the LED.)
Note 3 TH2 and TH9:
LPS:
CS circuit block: Set the self-diagnosis switch on the outdoor MAIN board as shown below.
• Check and make any corrections so that "0" is displayed.
• If any number other than 0 is displayed and TH2, TH9 or LPS are malfunctioning, correct them, then set
SW2-9 on the MAIN board of the outdoor unit from OFF to ON.
• If any number other than 0 is displayed and TH2, TH9 or LPS are not malfunctioning, replace the CS
circuit if refrigerant is not flowing through it (while operating) and set SW2-9 on the MAIN board of the
outdoor unit from OFF to ON.
Note 4 If it can be verified that R407C was correctly charged in the liquid phase, continue to Yes. If there is a
possibility that it was not charged correctly, such as with a gas charger, continue to No.
Note 5 After reclaiming the system's refrigerant, extract the air to create a vacuum, then refill with new refrigerant.
Be sure to charge in the liquid phase. In addition, be sure to change the dryer.
Note 6 After the units are operating stably, check that the refrigerant composition of αOC is within the following
ranges, indicating that the circulation check is finished.
If the accumulator liquid level AL = 0 when cooling:
If the accumulator liquid level AL = 1 when cooling:
When heating:
If the refrigerant composition of αOC is not within the ranges specified above, a large error has been
detected. Refer to section 1-3 in Chapter 6, then after setting SW4-1 on the MAIN board of the outdoor unit
to ON, calibrate the refrigerant circulation constant αOC with SW4-2 until it is within the ranges specified
above.
After calibrating, keep the SW4-1 ON and finish the circulation check.
<Example calibration of the refrigerant circulation constant αOC>
Conditions: If the accumulator liquid level AL = 0 and αOC = 0.29 when cooling, αOC must be adjusted so
that it is between 0.21 and 0.25.
By switching SW4-2 between ON and OFF, adjustments can be made in the following order:
0 → 3% → 6% → 9% → 12% → -6% → -3% → 0
For this example, by making an adjustment of -0.06 (-6%), αOC can be adjusted to 0.23.
[αOC self-diagnosis switch]
1 2 3 4 5 6 7 8 9 10
ON
Check and make any corrections using the same method as that for a faulty temperature
sensor, (refer to TROUBLESHOOTING).
Check and make any corrections using the same method as that for a faulty low pressure
sensor, (refer to TROUBLESHOOTING).
1 2 3 4 5 6 7 8 9 10
ON
1. If SW4-2 is already set to OFF, change the switch 5 times.
OFF (0.29) → ON (0.32) → OFF (0.35) → ON (0.38) → OFF (0.41) → ON (0.23)
2. If SW4-2 is already set to ON, change the switch 5 times.
ON (0.29) → OFF (0.32) → ON (0.35) → OFF (0.38) → ON (0.41) → OFF (0.23)
–175–
αOC = 0.20 ~ 0.26
αOC = 0.23 ~ 0.34
αOC = 0.25 ~ 0.34
αOC = 0.21 ~ 0.25
αOC = 0.24 ~ 0.28
αOC = 0.27 ~ 0.31