Bryant R-22 Troubleshooting HK38EA015 circuit board, Systems Communication Failure, Model Plug

MODEL

PLUG

UTILITY RELAY *

UTILITY SIGNAL

OPEN RELAY

MODEL

PLUG

LLS

* SUPPLIED BY UTILITY PROVIDER Liquid Line Solenoid

A06525/.A06526

Fig. 45 – 2-Stage Control Board

TROUBLESHOOTING

Troubleshooting (HK38EA015) circuit board

The Evolution Series outdoor units all use the same control board. A model plug is used to identify the system type, and set the operating parameters for airflow, start circuit timing etc. (see Model Plug section)

Replacement boards may have a different part number from the original board. A newer board will always be backward compatible to previous units if it is superseded at RCD. Old boards are not always forward compatible due to new functions, or software changes made to resolve field issues.

Systems Communication Failure

If communication with the Evolution control is lost with the User Interface, the control will flash the appropriate fault code. (See Table 21.) Check the wiring to the UI and the indoor and outdoor units.

Model Plug

Each control board contains a model plug. The correct model plug must be installed for or the system to operate properly. (See Table 18.)

The model plug is used to identify the type and size of unit to the control. On 286B models, the model plug is also used to determine the start sequence timing for each individual model.

On new units, the model and serial numbers are input into the board’s memory at the factory. If a model plug is lost or missing at initial installation, the unit will operate according to the information input at the factory and the appropriate error code will flash temporarily. An RCD replacement board contains no model and serial information. If the factory control board fails, the model plug must be transferred from the original board to the replacement board for the unit to operate.

NOTE: The model plug takes priority over factory model information input at the factory. If the model plug is removed after initial power up, the unit will operate according to the last valid model plug installed, and flash the appropriate fault code temporarily.

Pressure Switch Protection

The outdoor unit is equipped with high- and low-pressure switches. If the control senses the opening of a high- or low-pressure switch, it will respond as follows:

1.De-energize the appropriate compressor contactor.

2.Keep the outdoor fan operating for 15 minutes.

3.Display the appropriate fault code (see Table 21).

4.After a 15 minute delay, if there is a call for cooling or heating and LPS or HPS is reset, the appropriate compressor contactor is energized.

5.If LPS or HPS has not closed after a 15 minute delay, the outdoor fan is turned off. If the open switch closes anytime after the 15 minute delay, then resume operation with a call for cooling or heating.

6.If LPS or HPS trips 3 consecutive cycles, the unit operation is locked out for 4 hours.

7.In the event of a high-pressure switch trip or high-pressure lockout, check the refrigerant charge, outdoor fan operation, and outdoor coil (in cooling) for airflow restrictions, or indoor airflow in heating.

8.In the event of a low-pressure switch trip or low-pressure lockout, check the refrigerant charge and indoor airflow (cooling) and outdoor fan operation and outdoor coil in heating.

Control Fault

If the outdoor unit control board has failed, the control will flash the appropriate fault code (see Table 21). The control board should be replaced.

Brown-Out Protection

If the line voltage is less than 187v for at least 4 seconds, the appropriate compressor contactor and fan relay are de-energized. Compressor and fan operation are not allowed until voltage is a minimum of 190v. The control will flash the appropriate fault code (see Table 21).

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