Carrier 50CR installation instructions DefrostControl

50CR

CHECKING AND ADJUSTING REFRIGERANT CHARGE

The refrigerant system is fully charged with Puron (R-410A) refrigerant and is tested and factory sealed.

NOTE: Adjustment of the refrigerant charge is not required unless the unit is suspected of not having the proper R-410A charge. The charging label and the tables shown refer to system temperatures and pressures in cooling mode only. A refrigerant charging label is attached to the outside of the service access door. If charge level is suspect in heating mode, reclaim all refrigerant and charge to informative plate amount. (This information may be obtained from the physical data table also.) The charging label and the tables shown refer to system temperatures and pressures in cooling mode only. A refrigerant charging label is attached to the outside of the service access door.

IMPORTANT: When evaluating the refrigerant charge, an indicated adjustment to the specified factory charge must always be very minimal. If a substantial adjustment is indicated, an abnormal condition exists somewhere in the cooling system, such as insufficient airflow across either coil or both coils.

REFRIGERANT CHARGE

The amount of refrigerant charge is listed on the unit rating plate and/or the physical data table. Refer to the Refrigeration Service Techniques Manual, Refrigerants Section.

NO CHARGE

Check for leak. Use standard evacuating techniques. After evacuating system, weigh in the specified amount of refrigerant (refer to system rating plate).

LOW CHARGE COOLING

Use Cooling Charging Chart (Fig. 22). Vary refrigerant until the conditions of the chart are met. Note that charging charts are different from type normally used. Charts are based on charging the units to correct subcooling for the various operating conditions. Accurate pressure gauge and temperature sensing devices are required. Connect the pressure gauge to the service port on the suction line. Mount the temperature sensing device on the suction line and insulate it so that the outdoor ambient does not affect the reading. Indoor air CFM must be within the normal operating range of the unit.

TO USE COOLING CHARGING CHARTS

Take the liquid line temperature and read the manifold pressure gauges. Refer to the chart to determine what the liquid line temperature should be.

NOTE: If the problem causing the inaccurate readings is a refrigerant leak, refer to Check for Refrigerant Leaks section.

INDOOR AIRFLOW AND AIRFLOW ADJUSTMENTS

NOTE: Be sure that all supply- and return-air grilles are open, free from obstructions, and adjusted properly.

Unit 50CR utilizes state of the art ECM (Electronic Computated Motor) ID Blower Motors. See user interface instructions for detailed information on adjusting airflow.

Step 5—Defrost Control

QUIET SHIFT

Quiet Shift is a field-selectable defrost mode, which will eliminate occasional noise that could be heard at the start of defrost cycle and restarting of heating cycle. It is selected by placing DIP switch 3 (on defrost board) in ON position.

When Quiet Shift switch is placed in ON position, and a defrost is initiated, the following sequence of operation will occur. Reversing valve will energize, outdoor fan will turn off, compressor will turn off for 30 sec and then turn back on to complete defrost. At the start of heating after conclusion of defrost reversing valve will de-energize, compressor will turn off for another 30 sec, and the outdoor fan will stay off for 40 sec, before starting in the heating mode.

DEFROST

The defrost control is a time/temperature control which includes a field-selectable time period (DIP switch 1 and 2 on the board) between defrost cycles of 30, 60, 90, or 120 minutes (factory set at 30 minutes).

To initiate a forced defrost, two options are available depending on the status of the defrost thermostat.

If defrost thermostat is closed, speedup pins (J1) must be shorted by placing a flat head screw driver in between for 5 sec and releasing, to observe a complete defrost cycle. When the Quiet Shift switch is selected, compressor will be turned off for two 30 sec intervals during this complete defrost cycle, as explained previously. When Quiet Shift switch is in factory default OFF position, a normal and complete defrost cycle will be observed.

If defrost thermostat is in open position, and speedup pins are shorted (with a flat head screw driver) for 5 sec and released, a short defrost cycle will be observed (actual length is dependent upon the selected Quiet Shift position). When Quiet Shift switch is in ON position, the length of defrost is 1 minute (30 sec compressor off period followed by 30 sec of defrost with compressor operation). On return to heating operation, compressor will again turn off for an additional 30 sec and the outdoor fan for 40 sec. When the Quiet Shift is in OFF position, only a brief 30 sec cycle will be observed.

If it is desirable to observe a complete defrost in warmer weather, the defrost thermostat must be closed as follows:

1.Turn off power to outdoor unit.

2.Disconnect outdoor fan motor lead from OF2 on control board (See Fig. 23). Tape to prevent grounding.

3.Restart unit in heating mode, allowing frost to accumulate on outdoor coil.

4.After a few minutes in heating mode, liquid-line temperature should drop below closing point of defrost thermostat (approximately 30°F).

NOTE: Unit will remain in defrost until defrost thermostat reopens at approximately 80°F coil temperature at liquid line or remainder of defrost cycle time.

5.Turn off power to outdoor and reconnect fan motor lead to OF2 on control board after above forced defrost cycle.

NON-COMMUNICATING EMERGENCY COOLING / HEATING MODE

This mode of operation is provided only in the case where the UI has failed or is otherwise unavailable. If communications cannot be established with the UI, the Infinity control board will enable the following thermostat input terminals to allow simple thermostatic control of the 50CR unit:

a.Y & O for cooling

b.W for electric heat (if applicable)

c.Y for heat pump heat

The Infinity control will respond to cooling and heating demands with the maximum safe airflow based on electric heat size (if applicable) and unit capacity.

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