Figure 7.16 Adapter And O-Ring; Troubleshooting P6-7 (Duv) - Carrier PrimeLINE 69NT40-561-200 Operation And Service Manual

5. Replace the filter drier. Refer to
6. Evacuate to 500 microns by placing vacuum pump on liquid line and suction service valve.
7. Check economizer expansion valve superheat (see

7.23 TROUBLESHOOTING P6-7 (DUV)

A failed digital unloader valve (DUV), which is normally closed, or an internal seal failure of the compressor can
result in the unit running continually in the fully loaded mode causing it to undershoot its setpoint temperature.
Both of these conditions can be evaluated by running pre-trip test P6-7. When running P6-7, the controller is look-
ing for the differences in pressure and current draw between loaded mode and unloaded mode to make a judg-
ment. If there are no differences, then it will show fail.
To confirm what caused the test to fail, perform the following additional test.
1. Connect the manifold gauge set to discharge service valve (DSV) and suction service valve (SSV).
2. Front seat the SSV and pump down the compressor.
3. Front seat the DSV valve to isolate the compressor.
4. Disconnect the DUV from the top of compressor and install a 1/2 to 1/4 flared adapter / O-ring (P/N 40-
50076-00sv).
5. Using refrigerant (R-134a or R-513A as specified for the unit model number) or Nitrogen, pressurize the line
to 50 psi (3.5 bar) at the adapter connection and close supply at the tank. Pressure should hold as the valve
is normally closed. If pressure drops, check for leaks at the installed fitting (part number 40-50076-00sv);
repair and retest. If pressure increases at the suction service valve and decreases at the pressure supply;
the valve is leaking and should be replaced. If no leak proceed to step 6.
6. Energize the DUV by removing the coil and placing a magnet on the valve stem opening the valve. If the
pressure does not increase at the SSV and decrease at the supply, replace the valve as it did not open.
If a magnet is not available, a jumper procedure can be used as follows:
1. Remove all four controller fuses (F1, F2, F3a, F3b).
2. Remove the KA6 wire from the KA controller connector on the front of the controller.
3. Disconnect the X1 wire from the 24VAC side of the transformer (black wire) and locate it away from the
transformer.
4. Jumper between the black transformer wires to the KA6 wire removed from the connector.
5. Connect power to the unit and turn the circuit breaker on. The DUV coil is now energized.
6. Pressure should drop.
7. Power the circuit breaker off, reconnect wires and reinstall fuses.
8. If the valve opens and closes properly, the failure mode is with the compressor and it should be changed at
the earliest opportunity.
T-362
Section 7.14.

Figure 7.16 Adapter and O-Ring

1/2"
O-Ring
7–26
Section 3.2).
1/4"