Thermo King UT-1200, Manual

Page: 119 / 169

Refrigeration Service Procedures
119
3. The Maintenance Menu Hourmeters will
appear. Press the NEXT key as required to
show Evacuation Test. When the Evacuation
Test is shown press the SELECT key.
Figure 195: Select Evacuation Test
4. The display will indicate that the Evacuation
Mode is being programmed.
Figure 196: Programming
5. Turn the unit off.
Unit Evacuation
NOTE: Do not attempt to evacuate the unit until
the evacuation equipment has been tested and its
performance has been verified.
1. Prepare the unit for evacuation. Recover
refrigerant to 0 psig (0 kPa).
NOTE: Federal Regulations require your
recovery machine to pull the system’s
pressures lower than 0 psig [0 kPa].
2. If the unit has an ETV, put the unit into the
Evacuation Mode (see “Using Evacuation
Mode” on page 118).
3. Install the evacuation station hoses on the
receiver tank outlet valve, suction service
valve, and discharge service port. A low loss
fitting must be used on the hose connected to
the discharge service port.
4. Mid-seat the receiver tank outlet valve and
suction service valve, and install the valve
stem caps.
5. Connect a gauge manifold and refrigerant
supply to the charging port above valve V-4.
Bottle valve closed.
6. Start the vacuum pump and open valves V-1,
V-2, V-3, V-4.
7. Evacuate the refrigeration 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. The micron gauge reads
“ATM” if there is a leak to the atmosphere.
See Figure 197 on page 120.
8. When the desired micron level has been
achieved (500 to 1000 microns), close valve
V-1, stop the pump.
9. Observe the reading on the micron gauge after
5 minutes 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.
(See the Figure 197 “Pressure Rise
Graphs” on the next page.)
• If the vacuum level is acceptable, proceed
to unit charging.
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 thoroughly
leak checked and all leaks must be
repaired.