Thermo King KD-II SR, Manual

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Refrigeration Maintenance (Rev. 04/03)
96
7. Evacuate hoses to 100 microns or lowest achievable
level below 500 microns.
8. Once 100 microns is reached, close valve V-1 at the
pump. Turn the vacuum pump OFF.
9. Observe the micron gauge reading. The vacuum rise
should not exceed 1500 microns in 5 minutes.
10. If the rise is above 1500 microns in 5 minutes, check all
hoses and connections for leaks. Hoses with moisture
present will require additional evacuation time to
achieve satisfactory results.
NOTE: Dirty vacuum pump oil or a defective vacuum
pump will prevent a low micron reading. Hoses and
fittings can be isolated individually to identify leaks.
Unit Evacuation
NOTE: Refer to the diagram on the next page for the fol-
lowing discussion.
NOTE: Do not attempt to evacuate the unit until the evac-
uation equipment has been tested and its performance has
been verified.
1. Prepare the unit for evacuation. Recover refrigerant to 0
psig (0 kPa). (New Federal Regulations may require
your recovery machine to pull the system’s pressures
lower than 0 psig [0 kPa]).
CAUTION: Do not attempt to evacuate a unit until
you are certain that the unit is leak free. A unit with
less than a full refrigerant charge should be thor-
oughly leak checked and all leaks must be repaired.
2. Before connecting the evacuation hoses to the unit,
close valves V-1 and V-4 on the evacuation system.
Turn the micron gauge ON.
3. Back seat the suction, discharge and recover tank ser-
vice valves. Attach evacuation hoses to these three
valves. (Check condition of the hose seals.)
4. With the service valves fully back seated, turn the evac-
uation pump ON. Open valve V-1 at the pump. The
micron gauge should move to a deep vacuum.
5. Open valve V-4. The micron reading will rise. If the
micron gauge returns to a reading of less than 500
microns, proceed to step 6. If the micron reading
remains high, then a leak exists at the hose fittings or
the packing glands. Locate and correct the problem
before proceeding.
6. If step 5 was successful, close valve V-2 to isolate the
thermistor. Open the suction, discharge and receiver
service vales to port. Install brass and steel valve stem
covers (with sealing washers) on the service valves and
tighten. The vacuum pump continues to operate.
7. After 5 minutes of evacuation, open valve V-2 to access
the thermistor and micron gauge. The micron reading
now reflects the unit’s pressure.
8. Evacuate the system to 500 microns or the lowest
achievable level between 500 and 1000 microns.
NOTE: The presence of refrigerant in the compressor
oil may prevent a low micron reading from being
achieved. The oil can continue to “outgas” for long
periods of time. If the micron level appears to stall
after 1/2 hour or 45 minutes between 1000 and 1500
microns, back seat the suction service valve and
observe the micron gauge. A sharp drop in the micron
reading (300 to 500 microns) would indicate that
refrigerant is present in the oil or a leak exists in the
compressor area.
9. When the desired micron level has been achieved (500
to 1000 microns), close valve V-1 at the pump. Turn the
pump to OFF.
10. Observe the reading on the micron gauge after 5 min-
utes have elapsed. The vacuum rise should not exceed
2000 microns. If the vacuum level exceeds 2000
microns after 5 minutes, a leak is present or additional
evacuation time is required.