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4-2
T-283
4.3
INSTALLING MANIFOLD GAUGES
The manifold gauge set can be used to determine system
operating pressures, add charge, equalize or evacuate the
system. (See figure 4-2.)
Hand Valve
(Open)
Hand Valve
(Frontseated)
Low Pressure
Gauge
High Pressure
Gauge
A
B
C
A
. Connection to
Low Side of System
C
. Connection to Either:
Vacuum Pump
Refrigerant Cylinder
Oil Container
Evacuation Line
B
. Connection to
High Side of System
Figure 4-2. Manifold Gauge Set
The manifold gauge in figure 4-2 shows hand valves,
gauges and refrigerant openings. When the low pressure
hand valve is frontseated (turned all the way in), the low
(evaporator) pressure can be checked. When the high
pressure hand valve is frontseated, high (condensing)
pressure can be checked. When both valves are open
(turned counterclockwise), high pressure vapor will flow
into the low side. When the low pressure valve is open,
the system can be charged or evacuated. Oil can also be
added to the system.
Install the manifold gauge set as follows:
a. Remove both service valve stems and service port
caps. Backseat (counterclockwise) both service
valves.
b. Connect the high side hose tightly to discharge
service valve port.
c. Connect the low side hose loosely to suction service
valve port.
d. Loosen charging (center) hose at dummy fitting of
manifold set.
e. Frontseat (clockwise) both manifold gauge hand
valves.
f. Open discharge service valve counterclockwise
approximately 1/4 to 1/2 turns.
g. Slowly open (counterclockwise) manifold discharge
hand valve approximately one turn.
h. Tighten charging hose onto dummy fitting.
i.
Slowly open the manifold suction hand valve to
remove air from line.
j.
Tighten suction hose at the suction service valve port.
k. Frontseat (close) both manifold hand valves.
l.
Open suction service valve counterclockwise
approximately 1/4 to 1/2 turns.
4.4
PUMPING THE SYSTEM DOWN OR
REMOVING THE REFRIGERANT CHARGE
NOTE
To avoid damage to the earth’s ozone layer, use a
refrigerant recovery system whenever removing
refrigerant.
4.4.1 System Pumpdown
To service or replace the filter-drier, expansion valve,
evaporator coil, or suction line, pump the refrigerant into
condenser coil and receiver as follows:
a. Install manifold gauge set. (Refer to section 4.3.)
NOTE
The following procedure may have to be
repeated several times to maintain the 1 psig (6.9
kPa)
pressure depending upon amount of
refrigerant absorbed in the oil.
b. Frontseat filter-drier inlet service valve by turning
clockwise. Start system and run in cooling. Stop the
unit when the suction pressure reaches 1 psig (6.9
kPa)
to maintain a slight positive pressure.
c. Frontseat (close) suction service valve to trap the
refrigerant in the high side of the system between the
compressor suction service valve and the filter drier
inlet valve. The low side of the system will now be at 1
psig (6.9 kPa) pressure and ready for servicing,
d. Service or replace the necessary component on the
low side of the system.
e. Leak check connections. (Refer to section 4.5.)
f. Evacuate and dehydrate the low side. (Refer to
section 4.6.)
4.4.2 Removing the Refrigerant Charge
Connect a refrigerant recovery system to the unit near
the receiver to remove refrigerant charge. Refer to
instructions provided by the manufacturer of the
refrigerant recovery system.
NOTES
a. Before opening up any part of the system, a
slight positive pressure should be indicated on
the gauge.
b. When opening up the refrigerant system,
certain parts may frost. Allow the part to
warm to ambient temperature before
dismantling; this avoids internal
condensation, which puts moisture in the
system.
4.5
REFRIGERANT LEAK CHECK
A refrigerant leak check should always be performed
after the system has been opened to replace or repair a
component.
To check for leaks in the refrigeration system, perform
the following procedure:
Summary of Contents for CAPRI-280
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Page 39: ...5 2 Figure 5 1 Electrical Wiring Schematic Diagram Drawing No 62 10112 00 Sheet 1 of 3...
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