Bosch BMS500-AAU036-1AHCXC - Electronic Expansion Valve (EXV) Operation

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Service Manual
Bosch Climate 5000 Series Ductless Air Conditioner / Heat Pump Multi Zone Outdoor Units (01.2023)
When low ambient cooling is in effect:
f Outdoor fan speed control logic (low ambient cooling)
f When T4 < 15 °C (59 °F) and T3 < 30 °C (86 °F), the unit enters into low
ambient cooling mode. The outdoor fan chooses a speed according to T3.
f When T3≥38 ℃ (100.4 ℉) or when T4≥15 ℃ (59 ℉), the outdoor fan
chooses a speed according to T4 again.
Figure 34
38
Exit low ambient cooling
mode
, run with high fan
for 1 minute
Low
30
27
23
off
Figure 35
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7.4.3.2 Heating Mode
Under normal operating conditions, the system chooses a running fan speed
according to ambient temperature:
Figure 36
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7.4.4 Electronic Expansion Valve (EXV)
For Max Performance 48K System:
1. After the outdoor unit is powered on again, the EXV is first closed -520P,
and then in standby mode (if the current mode is heating mode, the initial
heating degree is run, otherwise the initial cooling degree is run, and the
internal machine is not connected. deal with 7k unit). The main valve first
opens 510P, then opens 530P, and then is in the standby state (if the current
outdoor mode is the heating mode or the standby mode, it maintains 0P, and
the cooling mode opens to the initial cooling opening). The EVI valve opens
510P first, then 530P, then the counter is cleared to 0P.
2. After the compressor is stopped,
a. If the EVI valve has a valve opening action before the stop, the PMV_
CLOSE_EE step is closed in the reverse direction after the stop, and
then the EXV opening counter is cleared to 0P. If the EVI valve does not
operate before the stop, 0P will be maintained.
b. Reverse the valve to close the PMV_CLOSE_EE step (after closing the
valve to the 0P, and then continue to run PMV_CLOSE_EE in the valve
closing direction, the EXV opening counter is cleared. If the current
opening is 300P, go to the valve Run the 320P in the closing direction to
close the EXV.), then in the standby state (if the current outdoor mode is
the heating mode, the initial heating opening is run, otherwise the initial
cooling opening is run, and the internal machine is not connected. deal
with 7k unit).
c. Main EXV action: When the compressor is off, the main EXV keeps
the opening degree when the compressor is turned off within the first
90 seconds. If it is currently heating mode, -20P, clear and keep 0P,
otherwise adjust to 480P.
4. Other EXV(except for EVI valve) cannot be operated at the same time. The
action priorityorder is A-B-C-D-E-main valve. The EVI valve can be operated
together with other EXV.