Carrier 30XW150-400 specifications Select 0% to close the valve

EXV TROUBLESHOOTING PROCEDURE — There are two different economizer EXVs. Both of the economizer EXVs have a total of 2785 steps. There are three different main EXVs, which all have a total of 4260 steps. The EXV motor moves at 150 steps per second. Commanding the valve to either 0% or 100% will add an additional 160 steps to the move, to ensure the valve is open or closed completely.

Follow the steps below to diagnose and correct EXV problems. Check EXV motor operation first. Switch the Enable/Off/Remote (EOR) Contact switch to the Off position. Check the appropriate circuit EXV, Circuit A EXV % Open (Circuit A EXV Position, EXV.A) or Circuit B EXV % Open (Circuit B EXV Position, EXV.B). The current value of 0 will be displayed. Increase the EXV position to select 100% valve position. The actuator should be felt moving through the EXV. To close the valve, select 0%. The actuator should knock when it reaches the bottom of its stroke. See Table 40 for a list of EXV modes and submodes.

If the valve is not working properly, continue with the fol- lowing test procedure:

Check the 8-position DIP switch on the board for the proper address (Fig. 10). Check the EXV output signals at appropriate terminals on the EXV module. For 30XW150,325 units, con- nect the positive test lead to EXV-J2A terminal 5 for Circuit A and to EXV-J2B terminal 5 for Circuit B.

For 30XW175,200,350,400 units connect positive test lead to EXV(X)-J2A terminal 5 for EXV(X) and EXV(X)-J2B ter- minal 5 for Economizer EXV(X). Using the Service Test pro- cedure on page 83, move the valve output under test to 100%. DO NOT short meter leads together or pin 5 to any other pin, as board damage will occur. During the next several seconds, carefully connect the negative test lead to pins 1,2,3 and 4 in succession. Digital voltmeters will average this signal and display approximately 6 vdc. If the output remains at a constant voltage other than 6 vdc or shows 0 volts, remove the connec- tor to the valve and recheck.

Select 0% to close the valve.

NOTE: When the valve is stationary, the output from the EXV board is 12-vdc.

See Tables 6 and 7. If a problem still exists, replace the EXV board. If the reading is correct, the expansion valve and EXV wiring should be checked. Check the EXV connector and interconnecting wiring.

1.Check color-coding and wire connections. Make sure they are connected to the correct terminals at the EXV board and EXV plug and that the cables are not crossed.

2.Check for continuity and tight connection at all pin terminals.

Check the resistance of the EXV motor windings. For 30XW150,325 units remove the EXV module plug EXV-J2A for Circuit A EXV and EXV-J2B for Circuit B EXV. For 30XW175,200,350,400 units remove the EXV module plug EXV(X)-J2A for main EXV and EXV(X)-J2B for economizer EXV. Check the resistance of the two windings between pins 1 and 3 for one winding and pins 2 and 4 for the other winding. The resistance should be 52 ohms (± 5.2 ohms). Also check pins 1-4 for any shorts to ground.

Inspecting/Opening Electronic Expansion Valves

IMPORTANT: Obtain replacement gaskets before opening EXV. Do not re-use gaskets.

To check the physical operation of an EXV, the following steps must be performed.

1.Close the liquid line service valve of the circuit to be checked. Put the Enable/Off/Remote Contact (EOR) switch in the Off position. Enter the Service Test mode

and change Service Test Enable, T.REQ from OFF to ON. A password may be required. Switch the EOR switch to the Enable position. Under the COMP sub- mode, enable one of the compressors (CP.xn) for the cir- cuit. Let compressor run until gage on suction pressure port reads 10 psig (68.9 kPa). Turn the compressor off. The compressor will turn off. Immediately after the com- pressor shuts off, manually close the actuated ball valve (ABV). If the unit is equipped with suction service valves and economizer service valves, close both valves. Clos- ing the valves will minimize the amount of charge that will have to be removed from the system after pump down.

2.Remove any remaining refrigerant from the system low side using proper recovering techniques. The economizer assembly has a 1/4-in. access connection which can be used to remove charge from the inlet of the EXVs. Turn off the line voltage power supply to the compressors.

CAUTION

Ensure refrigerant is removed from both the inlet and outlet of EXV assemblies. Equipment damage could result.

3.The expansion valve motor is hermetically sealed inside the top portion of the valve. See Fig. 43. Disconnect the EXV plug. Carefully unscrew the motor portion from the body of the valve. The EXV operator will come out with the motor portion of the device. Reconnect the EXV plug.

4.Enter the appropriate EXV test step under the (QUIC) Service Test mode Locate the desired item Circuit A EXV Position, EXV.A or Circuit B EXV Position, EXV.B. Change the position to 100%. Observe the opera- tion of the lead screw. See Fig. 43. The motor should be turning, raising the operator closer to the motor. Motor actuator movement should be smooth and uniform from fully closed to fully open position. Select 0% and check open to closed operation. If the valve is properly connect- ed to the processor and receiving correct signals, yet does not operate as described above, the sealed motor portion of the valve should be replaced.

Installing EXV Motor

IMPORTANT: Obtain replacement gasket before opening EXV. Do not re-use gaskets.

If re-installing the motor, be sure to use a new gasket in the assembly. See Fig. 44. It is easier to install the motor assembly with the piston in the fully closed position. Insert the motor into the body of the EXV. Tighten the motor to the body to 36 ft-lb (50 N-m) and then tighten the valve another 30 degrees.

Moisture Liquid Indicator — Clear flow of liquid refrigerant indicates sufficient charge in system. Bubbles in the sight glass indicate undercharged system or presence of noncondensables. Moisture in system, measured in parts per million (ppm), changes color of indicator. See Table 41. Change filter drier at first sign of moisture in system.

IMPORTANT: Unit must be in operation at least 12 hours before moisture indicator can give an accu- rate reading.

With unit running, indicating element must be in con- tact with liquid refrigerant to give true reading.

Filter Drier — Whenever moisture-liquid indicator shows presence of moisture, replace filter drier(s). There is one filter drier assembly on each circuit with two cores. Refer to the Car- rier Standard Service Techniques Manual, Chapter 1, Refriger- ants, for details on servicing filter driers.

61