4-17
3. Remove enclosing tube collar (item 4,
Figure 4-22) using installation/removal tool supplied
with repair kit (item 3).
4. Check plunger for restriction due to:
(a)
Corroded or worn parts; (b) Foreign material lodged in
valve; (c) Bent or dented enclosing tube.
5. Remove top plate, diaphragm spring, diaphragm
and body gaskets.
6. Install new parts, assemble in reverse order of
disassembly.
7. Torque the 4 capscrews to 40 inch pounds.
8. Do not overtighten enclosing tube assembly.
Torque to a value of 1.15 mkg (100 inch pounds).
9. Remove supplied installation/removal tool.
Install coil, and snap cap.
10. Dehydrate and evacuate the system. (Refer to
section 4.3) Charge unit with refrigerant per section 4.4.
11. Start unit and check operation.
4.25 SERVICING THE MODULATING
SOLENOID VALVE
NOTE
When repairing modulating valve with the
enclosing tube kit (CTD P/N 14-50021-01) be
sure not to remove items 7, 8 & 10. (See
Figure 4-23) Proper alignment of these items is
achieved only at the factory.
a. Coil Checkout Procedure
WARNING
Make sure power to the unit is OFF and power
plug disconnected before replacing the coil.
1. Disconnect the modulation valve coil wires from
their terminal locations (Refer to section 5).
2. Using a reliable digital ohmmeter, test each
lead’s resistance to ground. If the resistance indicates a
ground short is present, inspect the length of wiring for
damaged or exposed wires. Replace where necessary.
3. Setting the digital ohmmeter for low range check
coil’s resistance. If coil’s resistance is below 5 ohms it is
recommended to be replaced. New coils have an
approximate resistance of 7.6 ohms at 25
_
C (77
_
F). The
chart below gives the resistance of a new coil at various
ambient temperatures.
Ambient Temperature
Cold Coil
10
_
F
6.45 ohms
40
_
F
6.90 ohms
70
_
F
7.40 ohms
100
_
F
7.90 ohms
NOTE
A cold coil is a coil which had not been operating
and is assumed to be at ambient temperature. Hot
coil temperatures, taken after the unit has been
operating in deep modulation for a long period of
time, may give higher resistance readings.
4. Reconnect the modulation valve coil wires to
their correct terminal locations.
1
2
3
4
5
6
7
8
9
10
11
1. Coil Nut
2. Coil Nut O-ring
3. Coil Housing
4. Solenoid Coil
Sleeve
5. Solenoid Coil
6. Enclosing Tube
Assembly
7. Piston
8. Top Return Spring
9. Valve Body
10. Bottom Return
Spring
11. Filter
Figure 4-23. Modulating Solenoid Valve
b. Replacing the Coil
Remove locking nut and remove coil after
disconnecting wiring. When replacing nut, torque to a
value of 0.41 mkg (3 ft-lb).
c. To Replace Valve
1. Store the refrigerant in an evacuated container.
2. Remove two bolts from suction service valve.
3. Melt solder at modulating valve connection and
rotate valve and tubing enough to clear compressor.
Remove valve and tubing. Replace defective modulating
solenoid valve being careful to wrap body of replacement
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