Midea MCH2U-18PHH2 Service Manual page 22

average, the outdoor gives the following
modification commands:
---- If the T2B＞average, the relevant valve
needs to open 16p more
---- If the T2B= average, the relevant valve's
open range remains as is
---- If the T2B＜average, the relevant valve
needs to close 16p more
This modification is carried out every 2
minutes.
6.4.4.2 Heating Mode
The initial open angle of the EXV depends on
the size of the indoor model. The adjustment
range is 150-350p.
When the unit has been running for 3
minutes, the outdoor unit receives the indoor
units' indoor units' capacity demand and T2
information and then calculates their average.
After comparing each indoor unit's T2 with
the average, the outdoor gives the following
modification commands:
----If the T2＞average+2, the relevant valve
needs to close 16p more
---- If average+2≥the T2≥ average-2, the
relevant valve's open range remains as is
----If the T2＜average-2, the relevant valve
needs to open 16p more
This modification is carried out every 2
minutes.
6.4.5 Four-Way Valve Control
In heating mode, a four-way valve is opened.
In defrosting, a four-way valve operates
according to the current defrosting action.
In other modes, a four-way valve is closed.
When the unit is switched from heating to
other modes, the four-way valve turns off
after the compressor has been off for 2
consecutive minutes.
Failure or protection (excluding discharge
temperature protection and high/low
pressure protection) causes the four-way
valve to immediately shut down.
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