WD Catalog 2018

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9-7 - -
Evacuating and Charging the AC System
The primary use of a flushing kit is to remove contaminants from the AC
system hoses, evaporator, and condenser. Any other component of an AC
system should be bench checked or replaced, since flushing may be ineffective
or may damage a component. Flushing is usually performed after the recovery
process. We recommend it before you replace the compressor, or when you find
contamination in other components (receiver-drier, expansion valve, or connec-
tions). Some recover/recycle machines have optional “flush kits.” The only
proper way to flush system components is to use refrigerant in a closed-loop
system.
Evacuating and Charging the AC System
Evacuate the system once the air conditioner components are repaired or
replacement parts are secured, and the AC system is reassembled. Evacuation
removes air and moisture from the system. Then, the AC system is ready for
the charging process, which adds new refrigerant to the system.
Evacuating the System
Follow this procedure:
1. Tighten all connections and attach a vacuum pump to the
center hose of the gauge set.
MANIFOLD GAUGE SET
GAUGE CENTER HOSE
TO VACUUM PUMP
0
100
200 300
400
500
HIGH
TEMPERATURE
LOW
TEMPERATURE
150
120
90
60
30
0
10
20
30
GAUGE READINGS
FROM LOW SIDE
COMPRESSOR
SERVICE VALVE TO
VACUUM
PUMP
FROM HIGH SIDE
COMPRESSOR
SERVICE VALVE
HAND
VALVE
OPEN
HAND
VALVE
OPEN
LOW SIDE
READS IN
VACUUM
HIGH SIDE
READS BELOW
ZERO (0)
2. Start the vacuum pump and open both the hand valves on the
manifold all the way. Run the pump for five minutes, then
close the hand valves and shut off the pump.
3. Check the gauge readings for five minutes. If the gauge
needles move up, the system is not sealed. There is a leak. Air
and moisture are being sucked into the system by the
vacuum.
4. Tighten any loose connections. Re-start the pump, and open
the hand valves on the gauges again. Repeat the vacuum test.
Figure 9-3
This illustration shows
evacuation of an AC system
before recharging. It is very
important to run the
vacuum pump long enough
to insure the removal of any
moisture that may be in the
system.