Carrier 69NT40-561-300, Operation And Service Manual

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T-365 7–24
Set the PCnt (20%setting – DUV Modulation TEST).
If the compressor is able to unload, the compressor amperage and discharge pressure drops and the suction
pressure will climb – DUV is okay. If the discharge pressure does not decrease after the valve energizes,
replace the DUV.
Unloader Valve Solenoid coil cycles: 0 to 0.4 amp AC (AC/DC current clamp)
7.20 DIGITAL LOADER VALVE
7.20.1 Digital Loader Valve Replacement
1. Removing the DLV:
a. Pump down the compressor (refer to Section 7.4 ) and frontseat both suction and discharge valves. In
the event the DLV is stuck open and compressor cannot pump down, remove charge.
CAUTION
!
The scroll compressor achieves low suction pressure very quickly. Do not use the compressor
to evacuate the system below 0 psig. Never operate the compressor with the suction or dis-
charge service valves closed (frontseated). Internal damage will result from operating the com-
pressor in a deep vacuum.
b. Turn unit power off and remove power from the unit.
c. Loosen bolt on top of the DLV and remove coil assembly.
NOTICE
There is a small spacer tube between the top of the valve and the 12 VDC coil that needs to be
reinstalled into the solenoid valve coil. When removing the coil, it may fall out when lifted from the
valve body. Take care that the spacer is not lost; the valve will not function correctly without it.
d. Remove clamps holding the DLV to the discharge line.
e. Loosen the nuts attaching the DLV to the top of the compressor.
f. VALVE REMOVAL: The preferred method of removing the solenoid valve is to cut the connection
between the brazed section and the valve, using a small tube cutter. Remove valve.
Alternately, use a wet rag to keep valve cool. Heat outlet connection to valve body and remove valve.
g. Examine compressor and service valves. Ensure that the o-ring is not stuck in the gland of the valve.
h. Discard the o-ring on the o-ring face seal connection.
2. Installing the DLV:
a. Lubricate the gland shoulder area and o-ring with refrigerant oil.
b. Fit new valve in position and hand-tighten the o-ring nut.
c. Use a wet rag to keep valve cool while brazing. Braze DLV to service valve connection.
d. Reinstall and tighten the brackets that secure the valve body to the discharge line.
e. Torque o-ring face seal connections to 18 to 20 ft-lbs.
f. Install the coil onto the valve body and tighten the attachment bolt.
NOTICE
Confirm that the small spacer tube is inserted into the coil prior to attaching it to the valve
body. The valve will not function correctly without it.
g. Leak check and evacuate low side of unit as applicable. Refer to Section 7.6 .
h. Open service valves.