Thermo King 914970, Manual

Page: 119 / 186

Refrigeration Maintenance
119
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: New Federal Regulations may
require your recovery machine to pull the
system’s pressures lower than 0 psig [0 kPa].
2. Install hoses on the receiver tank, suction
service valve and discharge service port.
3. Connect a gauge manifold and refrigerant
supply to the spare access port on valve V-4.
Bottle valve closed.
4. Start the vacuum pump and open valves V-1,
V-2, V-3, V-4.
5. 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.
6. When the desired micron level has been
achieved (500 to 1000 microns), close valve
V-1 at the pump. Turn the pump to Off.
7. 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.
8. If the vacuum level is acceptable, start the
pump and open valve V-1 to evacuate the
pressure rise (5 minutes).
9. Close valve V-1 and stop the pump. Observe
the micron gauge to confirm that the system
remains in a deep vacuum. Close valve V-4.
The unit is ready to charge.
Refrigerant Leaks
NOTE: Refer to Diagnosing Thermo King
Refrigeration Systems (TK 5984-3-TM) for leak
detection procedures.
Use a reliable leak detector (e.g., electronic
detector) to leak test the refrigeration system.
Inspect for signs of oil leakage which is the first
sign of a leak in the refrigeration system.
NOTE: It is normal for comprssor shaft seals to
have a slightly oily film.
Unit Charging
NOTE: Unit must be leak checked and fully
evacuated before charging. Before charging,
make sure that the refrigerant lines from the
gauge manifold to the refrigerant supply bottle
have been evacuated or purged.
NOTE: Refer to the diagram on the next page
for the following discussion.
1. Back seat the suction service valve. The
discharge and receiver outlet valves remain
open to port.
2. Set the refrigerant supply bottle for liquid.
Open the gauge manifold hand valve, and
charge liquid refrigerant until the system has
the proper charge or until the system will take
no more liquid. If more charge is required,
charge will be added as a liquid through the
suction service valve if more refrigerant is
required.
3. After the liquid refrigerant is added, close the
gauge manifold hand valve.
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.