pressure at the compressor high side, a compound
gauge (0 to 250 psi and 0 to -30 inches of mercury) to
measure the low or suction side, valves to control
admission of these pressures to the gauges, and the
connections and lines required to connect the test set to
the system. Depending on test and service require-
ments, the test set can be connected to the low side, the
high side, a source of vacuum, a refrigerant cylinder, or
a refrigerant-recovery system. A swiveling hanger
allows you to hang the test set for easy access, and three
additional blank connections, not shown in the figure,
allow for securing the open ends of the three lines when
the test set is not in use.
HI
LO
There is always a path from the low-side input to
the low-side gauge and from the high-side input to the
LOW
HIGH
high-side gauge (fig. 11-24). Two valves control the
SIDE
SIDE
path of the refrigerant supply input. If the LO valve is
TO VACUUM OR
REFRIGERANT
open, the refrigerant supply input has a clear path to the
SUPPLY
ASf11023
Figure 11-23.--Refrigerant manifold test set.
low-side gauge and the low-side input. If only the HI
valve is open, the refrigerant supply input has a clear
refrigerant and accurately measuring pressures. If the
path to the high-side gauge and the high-side input. The
refrigerant cannot be contained within the system, the
hose in the center can be connected to a vacuum pump,
system will not operate due to low-pressure safety
a recovery-recycle system, or a refrigerant supply
devices. Or, if the high pressure (discharge) or the low
cylinder, depending on the type of servicing you wish
pressure (suction) is not within normal operating
to perform.
ranges, correct cooling temperatures will not be
PORTABLE VACUUM PUMP.--Another im-
achievable.
portant piece of equipment you will use is the portable
REFRIGERANT MANIFOLD TEST SET.--
vacuum pump. The type discussed here will be a single
One piece of equipment designed to measure pressure
piston vacuum pump driven by an electric motor. A
is the refrigerant manifold test set (fig. 11-23). The test
vacuum pump is the same as a compressor except that
set consists of a 0 to 500 psi gauge for measuring
the valves are arranged so that the suction valve is
HIGH-PRESSURE
LOW-PRESSURE
GAUGE
GAUGE
INSERT FOR
VALVE
TO
HIGH-PRESSURE
TO
TO
SERVICE VALVE
LOW-PRESSURE
VACUUM
SERVICE VALVE
PUMP OR
REFRIGERANT
SUPPLY
BLUE
YELLOW
RED
ASf11024
HOSE
HOSE
HOSE
Figure 11-24.--Internal view of refrigerant manifold test set.
11-25
