Carrier GTR040-420 Specifiche Scaricare il pdf (Pagina 52)

TROUBLESHOOTING

Compressor Protection Control System

(CPCS) Board —

The compressor protection board con-

trols the compressor and compressor crankcase heater.

The ground current protection is provided by the compres-

sor board.

The large relay located on the board is used to provide a

feedback signal to the Main Base Board.

The operation of the compressor board can be checked us-

ing the Service Test procedure. When the Service Test step is

turned on, the compressor board is energized. All safeties are

continuously monitored. The crankcase heater will be turned

off and the compressor contactor will be turned on. The feed-

back contacts will close and the Main Base Board (MBB) will

read the feedback status.

If the board does not perform properly, use standard wiring

troubleshooting procedures to check the wiring for open cir-

cuits. Refer to Alarms and Alerts section on page 53 for alarm

or alert codes for possible causes for failure.

If a compressor short-to-ground exists, the compressor

board may detect the short before the circuit breaker trips. If

this is suspected, check the compressor for short-to-ground

failures with an ohmmeter. The ground current is sensed with a

current toroid (coil) around all 3 or 6 wires between the main

terminal block and the compressor circuit breaker(s).

Compressor Ground Current (CGF) Board

(30GTN,R and 30GUN,R 130-210, 230A-315A,

and 330A/B-420A/B) —

One board is used for each

circuit of these units. Each board receives input from up to

4 toroids wired in series, one toroid per compressor. With 24 v

supplied at terminals A and B, a current imbalance (compres-

sor ground current) sensed by any toroid causes the NC

(normally closed) contacts to open, shutting down the lead

compressor in the affected circuit. All other compressors in that

circuit shut down as a result. The NC contacts remain open un-

til the circuit is reset by momentarily deenergizing the board

using the push-button switch.

If the NC contacts open, it is necessary to remove toroids

from the T1-T2 circuit to determine which toroid is causing the

trip. The chiller circuit can then be put back on line after the

circuit breaker of the faulty compressor is opened. The com-

pressor problem can then be diagnosed by normal trouble-

shooting procedures.

EXV Troubleshooting —

If it appears that the EXV is

not properly controlling operating suction pressure or super-

heat, there are a number of checks that can be made using

the quick test and initialization features built into the

ComfortLink™ control.

Follow the procedure below to diagnose and correct EXV

problems.

STEP 1 — CHECK PROCESSOR EXV OUTPUTS —

Check EXV output signals at the J6 and J7 terminals of the

EXV board.

Turn unit power off. Connect the positive lead of the meter

to terminal 3 on connector J6 on the EXV board. Set meter for

approximately 20 vdc. Turn unit power on. Enter and enable

the Service Test mode. Locate the appropriate EXV under

‘OUTS.’ Select the desired percentage and press Enter to move

the valve. The valve will overdrive in both directions when

either 0% or 100% are entered. During this time, connect the

negative test lead to terminals 1, 2, 4, and 5 in succession. The

voltage should fluctuate at each pin. If it remains constant at a

voltage or at 0 v, replace the EXV board. If the outputs are cor-

rect, then check the EXV.

To test Circuit B outputs, follow the same procedure above,

except connect the positive lead of the meter to terminal 3 on

connector J7 on the EXV board and the negative lead to termi-

nals 1, 2, 4, and 5 in succession.

STEP 2 — CHECK EXV WIRING — Check wiring to EXVs

from J6 and J7 connectors on EXV board.

1. Check color coding and wire connections. Make sure

that wires are connected to correct terminals at J6 and

J7 connectors and EXV plug connections. Check for

correct wiring at driver board input and output termi-

nals. See Fig. 2-4.

2. Check for continuity and tight connection at all pin

terminals.

3. Check plug connections at J6 and J7 connectors and at

EXVs. Be sure EXV connections are not crossed.

STEP 3 — CHECK RESISTANCE OF EXV MOTOR

WINDINGS — Remove connector at J6 and/or J7 of EXV

board and check resistance between common lead (red wire,

terminal D) and remaining leads A, B, C, and E. Resistance

should be 25 ohms ± 1 ohm. Check all leads to ground for

shorts.

STEP 4 — CHECK THERMISTORS THAT CONTROL

EXV — Check thermistors that control processor output volt-

age pulses to the EXVs. Circuit A thermistor is T7, and circuit

B thermistor is T8. Refer to Fig. 9 and 10 for location.

1. Refer to Thermistors section on page 64 for details on

checking thermistor calibration.

2. Make sure that thermistor leads are connected to the

proper pin terminals at the J5 connector on EXV board

and that thermistor probes are located in proper position

in the refrigerant circuit.

When these checks have been completed, the actual opera-

tion of the EXV can be checked by using the procedures out-

lined in Step 5 — Check Operation of the EXV section below.

STEP 5 — CHECK OPERATION OF THE EXV — Use the

following procedure to check the actual operation of the EXVs.

The ENABLE/OFF/REMOTE contact switch must be in the

OFF position.

1. Close the liquid line service valve for the circuit to be

checked and run through the appropriate service test to

pump down the low side of the system. Run lead com-

pressor for at least 30 seconds to ensure all refrigerant

has been pumped from the low side and that the EXV

has been driven fully open (1500 steps).

NOTE: Do not use the Emergency ON-OFF switch to

recycle the control during this step.

2. Turn off the compressor circuit breaker(s) and the control

circuit power and then turn the Emergency ON/OFF

switch to the OFF position. Close compressor service

valves and remove any remaining refrigerant from the

low side of the system.

3. Carefully loosen the 2

in. nut. Do not twist the valve.

Remove the motor canister from the valve body using

caution to avoid damage to the o-ring seal. If the EXV

plug was disconnected during this process reconnect it

after the motor canister is removed.

4. Note position of lead screw (see Fig. 15). If valve has re-

sponded properly to processor signals in Step 5.1 above,

the lead screw should be fully retracted.

5. Recycle the control by turning the Emergency ON-OFF

switch to the ON position. This puts the control in initial-

ization mode. During the first 60 seconds of the initializa-

tion mode, each valve is driven to the fully closed posi-

tion (1500 steps) by the processor. Observe the move-

ment of the lead screw. It should be smooth and uniform

from the fully retracted (open) to the fully extended

(closed) position.

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Carrier GTR040-420 Specifiche Pagina 52

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