Thermo King 098916, Maintenance Manual

Page: 139 / 196

Refrigeration Maintenance
138
Unit Preparation and Hookup
1. Recover all refrigerants from the unit and
reduce the unit pressure to the proper level
(US Federal Law requires a -17 to -34 kPa,
-0.17 to -0.34 bar, 5 to 10 in. vacuum that is
dependent upon the recovery equipment
used).
2. Break vacuum with refrigerant and equalize
system pressure to 0 kPa, 0 bar, 0 psig.
Replace the liquid line filter drier if necessary.
NOTE: Replace the one-piece filter drier
when major system contamination requires
evacuation and cleanup of the refrigeration
system.
3. Confirm that the evacuation station functions
properly. Determine “Blank Off” pressure.
The “Blank Off” pressure of the vacuum
pump is the deepest vacuum that the vacuum
pump can attain when isolated from the rest of
the system. The operator can be confident that
the pump and oil are in good condition, if a
vacuum pump (isolated from a system) is
started and the micron meter responds quickly
by going to a deep vacuum. If the vacuum
pump fails to reach a deep vacuum within 5
minutes, the operator should suspect the
condition of the oil or the pump. It is
recommended that the pump oil be changed
first to see if the rate of reaching a deep
vacuum is improved.
4. Connect the evacuation station and refrigerant
tank with gauge manifold (optional) to the
unit as indicated in figure Figure 87 on page
136. Connect evacuation hoses to the
compressor suction and discharge service
fittings.
5. Open Evacuation Station valves (V1, V3, and
V4). It is only necessary to open valve V2
when a reading on the micron meter is desired.
This is especially true when starting to
evacuate a unit and large amounts of moisture
and oil will be passing by the sensor.
6. Open the vacuum pump Iso-Valve™ built into
the pump housing below the handle. It is
recommended that the valve be kept open at
all times.
7. If connecting a refrigerant tank and gauge
manifold to the evacuation station, close the
gauge manifold and refrigerant tank valves to
prevent refrigerant from being drawn from the
tank.
CAUTION: Do not attempt to evacuate a
unit until it is certain that the unit is leak
free. A unit with less than a full charge of
refrigerant should be thoroughly leak
tested. Any leaks found must be repaired.