Carrier VECTOR 6500 Wartungshandbuch PDF herunterladen (Seite 273)

8−30

62-11389

FLOW

DIRECTION

1. Electronic Expansion

Valve

2. Coil Boot

3. Coil

4. Five Pin

Connector

Figure 8−28 Electronic expansion valve

a. Diagnostics - Microprocessor or Wiring

1. Locate the wires, on the engine harness side of the

EVXV connector labeled EXVA, EXVB, EXVC,

EXVD and EXVE. These will correlate to the connec-

tor pins labeled A, B, C, D and E. Refer to Table 8−4.

Table 8−4 EVXV Connections

Connector Pin Wire Color Winding

A ORANGE A

B RED B

C YELLOW

D BLACK

E GREY COM (+12V)

2. Set the voltmeter to the DCV scale. Ensure the unit is

disconnected from standby power and start the unit

in Standby Operation. Wait for the MessageCenter

to display “UNIT SHUTDOWN - SEE ALARM LIST”.

3. Perform the following test on the wiring coming from

the microprocessor:

Place the positive (+) voltmeter lead on pin E, the

negative (-) voltmeter lead on pin A and observe the

meter for several seconds. The voltage reading will

be very low, then rise to battery voltage (approxim-

ately 12.3VDC with a good battery) for a few

seconds, then drop back to a lower reading

4. Repeat for pins B,C and D.

5. If there is no voltage reading or if the voltage never

rises to battery voltage level, there is a problem in the

wiring or the microprocessor. Test all wiring from the

EVXV connector to the microprocessor and verify

good continuity before replacing the micropro-

cessor.

b. Diagnostics - Stepper Motor

The valve stepper motor may be tested using a stepper

motor drive tester or ohmmeter.

1. To test with a stepper motor drive tester (Carrier

Transicold part number 07-00375-00), connect the 5

pin test cable to the valve connector, and the cable

wires to the tester in accordance with wire and termin-

al color. (if a 5 pin tester cable is required, order Carri-

er Transicold part number 07-00375-11.)

2. Set the step rate to 50 steps per second and either

open or close the valve. Each red LED should light se-

quentially until all four are illuminated. Any LED failing

to illuminate indicates an open on that leg and a need

to replace the drive.

3. To test with an ohmmeter, check the winding resist-

ance between connector pin A & E, B & E, C & E and

then between D & E. In normal ambient, the resist-

ance between the pins should be 46 ohms. If an infin-

ite or zero reading is observed, the piston and drive

motor assembly is to be replaced.

c. Diagnostics - Valve

NOTE

If the valve failed Pretrip and passed the pre-

ceding diagnostic testing, this is an indication

that the valve internal mechanism is damaged

and the piston and motor assembly is to be re-

placed.

PIN A (ORANGE)

PIN B (RED)

PIN C (YELLOW)

PIN E (GRAY)

PIN D (BLACK)

COMMON

(+12VDC)

Figure 8−29 Electronic Expansion Valve

1. To test the valve internal mechanism, install a mani-

fold gauge set on the suction service valve and a

stepper motor drive tester. Refer to Section 8.8.6b.

2. Start the unit, set the step rate to 200 steps per

second (refer to Section 8.8.6 step b.) and close the

valve while watching the suction pressure. Within one

minute the suction pressure should begin to fall.

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