Daikin REYQ72-432XAYCU, Service Manual

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SiUS371901EB Check
Part 6 Service Diagnosis 426
4.5 Refrigerant Overcharge Check
In case of VRV Systems, the only way to judge as the overcharge of refrigerant is with operating
conditions due to the relationship to pressure control and electronic expansion valve control.
As information for making a judgment, refer to the information below.
Diagnosis of refrigerant overcharge
1. High pressure rises. Consequently, overload control is conducted to cause insufficient cooling
capacity.
2. The superheated degree of suction gas lowers (or wet operation is performed).
Consequently, the compressor becomes lower in discharge pipe temperature despite of
pressure loads.
3. The subcooled degree of condensate rises.
CHECK 6
Cooling
High press u re
Lo w press u re
Fre qu ency
High press u re
grad u ally rises w ith
increase in
fre
qu ency.
S ub cooling degree
b ecomes higher.
(Li qu id connection
pipe temperat u re
lo w ers.)
Lo w press u re rises d u e
to decreased
compressor o
u tp u t.
High press u re
Lo w press u re
Fre qu ency
Heating
The o u tdoor u nit electronic expansion v al v e
is closed d u e to the o v erload control.
Fre qu ency comes to
the minim u m le v el.
( High press u re is maintained
at a constant le v el.)
Lo w press u re rises
d u e to decreased
fre qu ency.
To maintain high press u re ,
fre qu ency decreases u nder the
capacity control.
High press u re drops or rises
immediately after the o v erload
control is complete.
Lo w press u re drops d u e to
closed o u tdoor u nit
electronic expansion v al v e.
Hot gas b ypass is acti v ated
for lo w press u re protection,
i.e., h u nting at lo w press u re .
Higher degree of o v ercharge
(Degree of o v ercharge)
Proper amo u nt
To maintain lo w press u re, fre qu ency
increases u nder the capacity
control.
Fre qu ency comes to
the minim u m le v el.
High press u re
dropping control
(Lo w press u re is
maintained at a
constant le
v el.)