4700 Refrigerated Sampler Service Guide
Section 3 Refrigeration System
3-11
Refrigerant leaks
Leaks are most likely to occur in the locations indicated by
arrows in Figure 3-15. A leak near the dryer or orifice is likely to
be caused by a drastic difference in temperature and pressure on
either side of the orifice. Other leaks may have been caused
during shipping or other physical shock.
Repair leaks with refrigeration-grade copper tubing, brazing the
ends with silver solder and properly covering all joints and
exposed metal from corrosive elements.
Tubing
Inspect all tubing for dents, bends, and cracks in the paint. The
tubing can be damaged if struck by a hard object, such as a tool
or a fan blade.
Tubing must be refrigeration-grade copper tubing, and must be
protected at all times from exposure to gases and other corrosive
elements. Gases can eat through the copper, making it porous
and prone to leaks and/or oxidized material clogging the line. All
brazed areas and exposed metal must be coated with lacquer
paint and then covered with shrink tubing.
Table 3-2 Refrigeration System Troubleshooting
Symptom
Cause
Action
Compressor tries to start, then
stops, has excessive current draw
Plugged orifice
Replace refrigeration module
(recommended)
Compressor failure
Compressor runs hot,
trips thermal breaker
Refrigerant leak
Outer coil does not heat up while
unit is running
Compressor does not start at all
Relay or capacitor failure
Replace component (see Table 3-1)
Higher than normal pressure on
one or both service ports
Refrigerant overfill
Drain and recharge the system
(see Section 3.4.2).
Water inside the tubing, forming ice
Dented, pinched, or bent tubing
Repair or replace damaged tubing.
Poor performance, compressor
running constantly
Air leak
Ensure that all adhesive and Permagum
sealants are properly placed on and
behind refrigeration module. See
Figures .1-8 and 1-9.
Poor performance even if running
normally
Air leak
Inspect the door gasket and the cork
tape insulation on the compressor suc-
tion line.
Sampler sitting in direct sunlight or
in high ambient temperatures
Improve the installation conditions if pos-
sible.
High ambient humidity
Clanging fan
Blades bent or blocked by debris
Straighten blades by hand, clear out
debris, secure mounting hardware
Fan not running
Fan motor failure
Replace fan
Summary of Contents for 4700
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