System Service - Daikin WGZ030DW Operating And Maintenance Manual

System Service

Service on this equipment is to be performed only by qualified refrigeration personnel. Causes
for repeated tripping of equipment protection controls must be investigated and corrected.
Disconnect all power before doing any service inside the unit or serious personal injury or death
can occur.
NOTE: Anyone servicing this equipment must comply with the requirements set forth
by the EPA concerning refrigerant reclamation and venting.
Filter-Driers
To change the filter-drier, pump the unit down (with the compressor running) by closing the
manual liquid line shutoff valve(s). The unit will start pumping down until it reaches the low-
pressure cutoff setting of 58 psi.
Close the discharge valve. Remove the refrigerant in the liquid line with a recovery unit to EPA
required pressure. Remove and replace the filter-drier(s). Evacuate the lines through the liquid
line manual shutoff valve(s) to remove noncondensables that may have entered during filter
replacement. A leak check is recommended before returning the unit to operation.
Liquid Line Solenoid Valve
The liquid line solenoid valve(s), which are responsible for automatic pumpdown during
normal unit operation, do not normally require any maintenance. However, in the event of
failure they can require replacement of the solenoid coil or of the entire valve assembly.
The solenoid coil can be removed from the valve body without opening the refrigerant piping
by moving pumpdown switch(es) PS1 and PS2 to the "manual" position.
The coil can then be removed from the valve body by simply removing a nut or snap-ring
located at the top of the coil. The coil can then be slipped off its mounting stud for
replacement. Be sure to replace the coil on its mounting stud before returning pumpdown
switch(es) PS1 and PS2 to the "auto pumpdown" position.
To replace the entire solenoid valve, follow the steps for changing a filter-drier.
Thermostatic Expansion Valve
The expansion valve is responsible for allowing the proper amount of refrigerant to enter the
evaporator regardless of cooling load. It does this by maintaining a constant superheat.
(Superheat is the difference between refrigerant temperature as it leaves the evaporator and the
saturation temperature corresponding to the evaporator pressure). All WGZ chillers are factory
set for between 8°F and 12°F (4.4°C to 6.7°C) superheat at full load.
To increase the superheat setting of the valve, remove the cap at the bottom of the valve to
expose the adjustment screw. Turn the screw clockwise (when viewed from the adjustment
screw end) to increase the superheat and counterclockwise to reduce superheat. Allow time for
system rebalance after each superheat adjustment.
The expansion valve, like the solenoid valve, should not normally require replacement, but if it
does, the unit must be pumped down by following the steps involved when changing a filter-
drier.
If the problem can be traced to the power element only, it can be unscrewed from the valve
body without removing the valve, but only after pumping the unit down.
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DANGER
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OM 1130-2