A LOOK AT SERVICE SAFETY
Installation and Replacement Information
103
V.
Service Valves
As shipped with the compressors, the rotolock ser-
vice valves have a small plastic dust plug inside the
threaded end. Be sure to remove this plug before
installing.
Service valves on Tecumseh systems are “front
seated” by turning the valve stem clockwise. This
closes the valve and opens the gauge port.
Turning the stem counter-clockwise “back seats” the
valve and thus opens the system and closes the gauge
port.
If present, the valve port to the system control (high
pressure cutout, low pressure control, fan control
etc.) is always open regardless of the position of the
valve stem.
If it is desired to operate the system with the service
gauge operating, it is necessary to “crack” the valve
from its back seated position for the gauges to per-
form. Before removing the gauges, close the gauge
port by returning the valves to their fully open posi-
tion (back seated).
Remember to check the packing gland nut (if
present) on the stem for snugness before leaving the
job. Install the cover nut over the valve stem as a sec-
ondary safeguard against leaks at the stem.
VI.
Processing the System
The performance and longevity of a refrigeration
system is strongly influenced by how the system was
“processed,” that is, how the system was prepared for
operation at the time of installation. The procedure
is:
1. On split systems, install the liquid and suction
line. See “Refrigerant Line Sizes” on pages 88-
92 for recommended line sizes. A properly
sized suction line accumulator is recom-
mended. See “Accumulator Selection Data” on
page 118 for accumulator sizing. Insulate the
suction line to reduce heat exchange and
excessive return gas temperatures to the com-
pressor.
2. To prevent oxidation and scale forming inside
the tubes, it is good practice to flow dry nitro-
gen through the tubing during the soldering
operations. A light flow of about 1/4 cubic feet
per minute is sufficient.
3. Install a filter in the liquid line immediately
ahead of the capillary tube or expansion valve.
A liquid line drier should also be installed.
4. A suction line filter/drier is recommended to
protect the compressor. A suction accumulator
must be installed on those systems having
defrost cycles (heat pumps, low temperature
refrigeration) or the likelihood of periodic
floodbacks (bulk milk coolers, ice machines).
See “Accumulator Selection Data” on page 118
for accumulator sizing.
5. Pressure test the system for leaks using the
safety precautions outlined in “System Flush-
ing, Purging, and Pressure Testing for Leaks”
on pages 4-5. Do not pressurize the system
beyond 150 PSIG field leak test pressure.
6. Use a vacuum pump (not a compressor) to
draw a vacuum of 1000 microns or less from
both sides of the system. It is a waste of time to
attempt to draw a vacuum on a system with
the pump connected only to the low side.
Entry must be made directly into the high
pressure side to properly evacuate that portion
of the system. Use a good electronic gauge to
measure the vacuum. An accurate reading can-
not be made with a refrigeration gauge.
Remember 29” of mercury as read on a com-
pound gauge equals 23,368 microns of vac-
uum.
WARNING!
Never use a compressor to
evacuate a system. Instead, use a high vac-
uum pump specifically designed for that pur-
pose.
Never start the compressor while it is under
deep vacuum. Always break a vacuum with
refrigerant charge before energizing the
compressor.
Failure to follow these instructions can dam-
age the hermetic terminal and may result in
terminal venting. As always, to reduce the
risk of serious injury or death from fire due
to terminal venting, never energize the com-
pressor unless the protective terminal cover
is securely fastened.
