Mitsubishi Electric CITY MULTI PUHY-400YMF-C Service Handbook page 74

(12) Control at initial starting
• When the ambient temperature is low (5˚C or less in cooling and – 5˚C or less in heating), initial starting will be
performed if the unit is started within 4 hours of the power being turned on.
• The following initial start mode will be performed when the unit is started for the first time after the power has
been turned on.
<Flow chart of initial start mode>
At the completion of Step
2, if the frequency of No.1
compressor is below the
specified value and if Step
2 has been completed less
than 3 times, the process
does not proceed to Step 3
but rather enters the
Pause Step and then
repeats Step 2.
Start of initial operation mode
Step 1
• Only the No.1 compressor is operated (f
• Operation of the No.2 compressor is prohibited.
• Finished when cumulative operating time reaches
30 minutes.
Pause Step
• Both compressors are stopped, regardless of the
demand from the indoor units. (3 minutes)
Step 2
• Only the No.1 compressor is operated.
• Operation of the No.2 compressor is prohibited.
• Operates continuously for 10 minutes and finishes.
Step 3
• Both compressors, No.1 and No.2, are operated
(Forced)
• Finished when cumulative operating time reaches
30 minutes.
Initial operation mode is finished.
-71-
75 Hz)