RXF ROTARY SCREW COMPRESSOR UNITS
OPERATION
070.410-IOM (JAN 12)
Page 15
18 - 20 for correct installation of gaskets and location of
solenoids.
OUT
OUT
GASKET INSTALLATION
SIDE VIEW
PRESSURE
PRESSURE
COMMON
COMMON
VENT
YY3
YY4
Figure 18 - RXF 12–19 Vi Control
Figure 19 - RXF 24–50 Vi Control
Figure 20 - RXF 58–101 Vi Control
SLIDE VALVE CALIBRATION
Slide valve calibration is performed on the Quantum™LX
control panel in automatic mode. If further problems occur
or persist, contact Johnson Controls-Frick service.
COMPRESSOR UNLOADING:
The compressor unloads when
MSV solenoid YY1 is energized and oil is allowed to flow
from compressor port 2 thru the needle valve to the MSV
solenoid. This allows discharge pressure on the slide valve
piston to unload the slide valve as the piston moves outward.
ADJUSTMENT (Capacity Control):
A needle valve (HV2)
is provided to adjust slide valve travel time, preventing
excessive slide valve “hunting”. HV2 should be adjusted to
restrict oil flow to the compressor port so that slide valve
travel time from full load to full unload, or vice versa, is a
minimum of 30 seconds.
NOTE: A change in operating conditions, such as winter-
to-summer operation, may require readjustment of slide
valve travel time.
VOLUMIZER
®
II Vi CONTROL
The RXF compressor is equipped with a special internal
control that automatically adjusts the compressor volume
ratio to the most efficient of three available steps, (2.2, 3.5,
or 5.0 volume ratio). This gives the compressor the ability
to operate at varying operating conditions while minimizing
power consumption by avoiding over or undercompression.
Solenoid valves 3 and 4 (See Figures 18 - 20 and location
on P & I diagram represented by YY3 and YY4) control the
Volumizer
®
II volume ratio control. Oil is internally ported
to apply hydraulic pressure to two stepping pistons in order
to move the moveable slide stop to the optimum position.
The following chart shows the logic of solenoid operation
to adjust the volume ratio.
Vi
SOLENOID 3 / YY3
SOLENOID 4 / YY4
2.2
Energized
Energized
3.5
Deenergized
Energized
5.0
Deenergized
Deenergized
Proper operation of the Volumizer
®
II control can be checked
as follows.
1. Confirm that the slide valve travel number in Factory Setup
is set at 190 degrees. If necessary, adjust the setting to 190
degrees before proceeding further.
2. Set the compressor Vi to 2.2, then record the voltage that
is shown on the Slide Valve calibration screen for the cur-
rent Slide Valve and 0% Slide Valve positions. The difference
between these voltages must be in the 1.35 - 1.65 Vdc range.
3. Set the compressor Vi to 3.5, then record the voltage that
is shown on the Slide Valve calibration screen for the cur-
rent Slide Valve and 0% Slide Valve positions. The difference
between these voltages must be in the 0.95 - 1.15 Vdc range.
4. Set the compressor Vi to 5.0, then record the voltage that
is shown on the Slide Valve calibration screen for the cur-
rent Slide Valve and 0% Slide Valve positions. The difference
between these voltages must be in the 0.73 - 0.93 Vdc range.
5. If the above voltage measurements are all in range, the
Volumizer
®
II is working properly. If any of the voltages are
out of range, go to the troubleshooting section.
Proper installation of the Vi control valves and gaskets is
essential to the operation of this equipment. Incorrectly
installed parts may cause the compressor to operate at the
wrong Vi, or to load or unload improperly. Operation at the
wrong compressor Vi can cause excessive power consump-
tion, noise, vibration, or excessive oil foaming. See Figures
