Carrier Omnizone 50XCR06-24 Installation, Start-Up And Service Instructions Manual Download Page 20

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Compressor Rotation

To determine whether or not compressor is rotating in the proper

direction:

1. Connect service gages to suction and discharge pressure

fittings.

2. Energize the compressor.
3. The suction pressure should drop and the discharge pressure

should rise, as is normal on any start-up.

4. If the suction pressure does not drop and the discharge pres

sure does not rise to normal levels, the compressor may be

rotating in the wrong direction.

5. Since the compressor and fan motors are connected in phase

during production, it is likely that the evaporator and con

denser fans are probably also rotating in the wrong direction.

6. Turn off power to the unit, lock and tag disconnect per stan

dard safety procedures.

7. Reverse any two of the unit power leads.
8. Remove lock and tag per standard safety procedures and

reapply power to the unit.

9. The suction and discharge pressure levels should now move

to their normal start-up levels.

NOTE: When the compressor is rotating in the wrong direction,

the unit makes an elevated level of noise and does not provide

cooling.

Operating Sequence

All units require the addition of a thermostat accessory package to

complete the control circuit. The sequence of operation may vary

depending on which package is selected.
ROOM-MOUNTED THERMOSTAT
These units use an electronic thermostat mounted in the condi

tioned space.
FAN CIRCULATION
The indoor-fan motor is energized through G on the thermostat

and the indoor-fan contactor is energized. This starts the indoor-

fan motor (IFM). The fan will operate to provide continuous air

circulation.
COOLING
The indoor fan will operate continuously or when the compressor

runs, depending on the setting of the thermostat fan selector

switch. When the thermostat closes (on a call for cooling Y1 on

the thermostat), the control relay (CR), outdoor-fan contactor

(OFC) and compressor contactor(s) (C1 and C2 on 50XCR12-16

units) close. The control relay will start the indoor fan if it is not

already running. The compressor contactors will immediately start

the first stage compressor(s).

A second stage on 50XCR12-16 units will close if additional cool

ing demand is required, and will then start the second-stage com

pressor. When the thermostat is satisfied, the second stage com

pressor will stop first, and then the first stage compressors will

stop when cooling demand is satisfied.
2-SPEED FAN OPERATION SEQUENCE
On the VFD the following parameters must be set on each unit. To

change the parameters:

1. Press MENU.

2. Select Parameters.
3. Press ENTER.
4. Select sub-group (first two digits of the parameters).
5. Press SEL.
6. Select parameter.

7. Press EDIT.
8. Select the new value (see Table 12).
9. Press SAVE.
10. Select any other parameters of the group to change and go to

Step 7.

11. When complete, press EXIT.
12. Select any other parameter groups to change and go to Step 5.
13. When complete, press EXIT.
14. Press EXIT until the status menu is visible (HZ, PSI)

Table 12 —

VFD Parameters

On the VFD, the following parameters must be loaded from the

IFM-VFD configuration keypad. The parameter list is provided

should the keypad be damaged and the points loaded manually

(see Table 13). To download parameters from the configuration

keypad:

1. Press MENU.

2. Select PAR backup.
3. Press SEL.
4. Select download to drive ALL.
5. Press SEL.
6. When download is complete press SEL.

Table 13 —

IFM - VFD Parameters

Should it be necessary to upload data to the configuration keypad:

1. Press MENU.

2. Select PAR backup.
3. Press SEL.
4. Select upload to panel.
5. Press SEL.
6. When download is complete, press SEL.
ALL UNITS
The control circuit incorporates a current sensing lockout relay

(Cycle-LOC™ device) that locks off the compressor(s) for 5 min

utes when any safety device is activated (low or high pressure

switches, or compressor internal overload). If any compressor

safety device opens, the compressor will stop. High and low-pres

sure switches and compressor motor overload protectors will reset

automatically when the condition which caused the device to trip

has dropped below the reset condition. To reset the Cycle-LOC

control device, manually turn the control power OFF, then back

ON.

PARAMETER

INDEX

PARAMTER