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Refrigeration Service Operations
147
3. With the piston pushed all the way back in its
bore, use a strong light to look down the
0.089 in. (2.26 mm) hole towards the back of
the piston and determine how much of the end
of the hole is covered by the piston. If the
piston covers more than three-quarters of the
hole replace the end cap.
NOTE: When front seating a condenser bypass
check valve DO NOT over-tighten the stem!
Excessive torque will deform the piston and the
deformed piston can increase the hole blockage.
Seat (Center Section) Orifice Check
There are three 0.033 in. (0.84 mm) holes located
in the three-way valve seat (center section). Only
one is used depending on how the valve is config-
ured. If the hole is too large the valve will be slow
to shift from heat to cool when the condenser
pressure is higher than discharge pressure because
gas will flow to the discharge line instead of
behind the piston. If the hole is too small the valve
will be slow to shift from heat to cool when dis-
charge pressure is higher than condenser pressure
because the flow is restricted.
Do not enlarge this
hole larger than 0.033 in. (0.84 mm)!
Whenever
you disassemble a three-way valve you should
check that all three of the holes are drilled cleanly.
Assembly/Installation
After cleaning and inspecting all parts, reassemble
the valve.
1. Install the screen in the bottom cap.
2. Install the new stem in the bottom cap.
3. Install new gaskets on both sides of the seat.
Oil the gaskets in compressor oil before
installing.
4. Use the three-way valve seal installation tool
P/N 204-1008 to install a new seal on the
piston. This prevents the seal from being
stretched and damaged.
a. Place the tapered tool over the piston.
b. Lubricate the seal with refrigeration oil.
c. Slide the seal onto the tapered tool with
the spring side facing away from the
piston.
d. Use the pipe to hand press the seal onto
the piston.
5. Place the piston slot on the stem and secure
with spring clip. The open part of the clip
should be on the opposite side of the piston
slot.
6. Install the spring and end cap.
7. Line up the passageways in the cap and body.
Failure to line up the holes will result in
improper operation of the valve.
8. Install the bolts and tighten in rotating
sequence. Torque to 160 in-lb (18 N•m).
1.
Number 66 Drill
Figure 231: Check Seat Orifice
1
1.
Press by Hand
4.
Tapered Tool
2.
Pipe
5.
Piston
3.
Seal
Figure 232: Seal Installation with Tool P/N 204-1008
1
ARA166
2
3
4
5