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COMPRESSOR OIL COOLER - RADIATOR TYPE (Figure 1-5, page 11) - The oil cooler motor and fan is
mounted on the oil cooler module; air is exhausted through the oil cooler and away from the unit. Do not
obstruct air flow to and from the oil cooler. Allow a minimum of three (3) feet clearance around the cooler.
Keep both faces of cooler core clean for efficient cooling of compressor oil.
THERMAL CONTROL (THERMOSTATIC MIXING) VALVE (Figure 5-9) is installed in system as shown
in Figure 5-3, page 68. This valve is used to control temperature of the oil in both air-cooled radiator and
water-cooled heat exchanger type oil cooler systems. On start-up with unit cold, element is open to
bypass, allowing oil to pass directly from the reservoir to compressor during warm-up. As oil warms,
element gradually closes to the bypass allowing more of the oil from the cooler to mix with oil from the
bypass.
After the unit is warmed up, the mixing valve maintains oil injection temperature into the compressor at a
minimum of 160° F (71° C). This system provides proper compressor warm-up and helps prevent
moisture contamination of oil.
To check element, heat in oil - it should be fully extended at 160° F (71° C). If unit shuts down due to
high air discharge temperature, it may be that one or both thermostatic mixing valve elements (Figure 5-3,
page 68) are stuck open. Remove mixing valve and clean all parts thoroughly when flushing the oil
system.
Compressor, air/oil reservoir, separation chamber and all piping and tubing
may be at high temperature during and after operation.
COMPRESSOR OIL COOLER - WATER-COOLED HEAT EXCHANGER (Figure 5-3, page 68) - The
heat exchanger oil cooler is a multiple pass type, with water in the tubes and oil in the shell. The oil
temperature is controlled by the thermal (thermostatic mixing) valve. The optional water control valve
may be used to conserve water.
Figure 5-9 – THERMOSTATIC MIXING VALVE ELEMENT
13-21-603
Page 77
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