McQuay seasoncon ALP-067A Installation And Maintenance Data page 41

Liquid Line Solenoid Valve
The liquid line solenoid valves, which are responsible for automatic
pumpdown during normal unit operation,
maintenance.
They may, however, require replacement of the solenoid
coil or of the entire valve assembly.
The solenoid coil may be removed from the valve body without opening
the refrigerant piping by moving pumpdown switches (PSl & PS2) to
the 1'man. pumpdown" position.
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 switches (PSl & PS2) to the "auto. pumpdown" po-
sition.
To replace the entire solenoid valve, the unit must be pumped down
by use of the manual liquid line shutoff valve.
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.
difference between refrigerant temperature as it leaves the evapor-
ator and the saturation temperature corresponding to the evaporator
pressure.)
Typically,
15F. On valves purchased through McQuay , the superheat setting can
be adjusted by removing a cap at the bottom of the valve to expose
the adjustment screw.
adjustment screw end) to increase the superheat setting and counter-
clockwise to reduce superheat.
ter each superheat adjustment.
I N L E T
The coil can then be removed from the
superheat should run in the range of 10F to
Turn the screw clockwise (when viewed from the
Allow time for system rebalance af-
do not normally require any
(Superheat is the
POWER ELEMENT
(CONTAINS DIAPHRAGM)
O U T L E T
SPRING
ADJUSTMENT SCREW
CAP
page 41