Carrier 25HPA6 instruction manual Pressure Switch Protection, Control Fault, Brown-Out Protection

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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 compressor contactor.

2.Keep the outdoor fan operating for 15 minutes.

3.Display the appropriate fault code (see Table 4).

4.After a 15 minute delay, if there is a call for cooling or heat- ing and LPS or HPS is reset, the 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 in- door 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 4). 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 4).

2230V Brown-Out Protection Defeated

The brownout feature can be defeated if needed for severe noisy power conditions. This defeat should always be a last resort to solving the problem. Defeat is available on the User Interface setup screen (available with SYSTXCCUID01-C), or can be initiated through the forced defrost pins for non-communicating systems as follows:

The brownout toggle is accomplished by sorting the defrost pins from power up with the OAT and OCT sensor connector removed. After 3 seconds, the status of the force defrost short and the OAT/OCT as open will be checked. If correct, then the brownout will be toggled.

Status code 6 shows the brownout is disabled. Status code 5 shows the brownout is active.

After the brownout defeat is set, power down and reinstall the OAT/OCT sensor and remove the short from the forced defrost pins. As long as the short on the forced defrost remains, the OAT and OCT faults will not be cleared. The code will continue to be flashed.

The control is shipped with the brownout active. The change in status is remembered until toggled to a new status. A power down/power up sequence will not reset the status. it may be necessary to do the toggle twice to cycle to the desired state of the defeat.

230V Line (Power Disconnect) Detection

If there is no 230v at the compressor contactor(s) when the indoor unit is powered and cooling or heating demand exists, the appropriate fault code is displayed. Verify the disconnect is closed and 230v wiring is connected to the unit.

Compressor Voltage Sensing

The control board input terminals labeled VS and L2 (see Fig. 6) are used to detect compressor voltage status and alert the user of potential problems. The control continuously monitors the high voltage on the run capacitor of the compressor motor. Voltage should be present any time the compressor contactor is energized and voltage should not be present when the contactor is de-energized.

Contactor Shorted Detection

If there is compressor voltage sensed when there is no demand for compressor operation, the contactor may be stuck closed or there may be a wiring error. The control will flash the appropriate fault code.

If the control senses the compressor voltage after start-up and is then absent for 10 consecutive seconds while cooling or heating demand exists, the thermal protector is open. The control de-energizes the compressor contactor for 15 minutes, but continues to operate the outdoor fan. The control Status LED will flash the appropriate code shown in Table 4. After 15 minutes, with a call for low or high stage cooling or heating, the compressor contactor is energized. If the thermal protector has not re-set, the outdoor fan is turned off. If the call for cooling or heating continues, the control will energize the compressor contactor every 15 minutes. If the thermal protector closes, (at the next 15 minute interval check) the unit will resume operation.

If the thermal cutout trips for three consecutive cycles, then unit operation is locked out for 4 hours and the appropriate fault code is displayed.

No 230V at Compressor Contactor

If the compressor voltage is not sensed when the compressor should be starting, the appropriate contactor may be stuck open or there is a wiring error. The control will flash the appropriate fault code. Check the contactor and control box wiring.

Troubleshooting units for proper switching between low & high stages

Check the suction pressures at the service valves. Suction pressure should be reduced by 3-10% when switching from low to high capacity.

Compressor current should increase 20-45% when switching from low to high stage. The compressor solenoid when energized in high stage, should measure 24vac.

When the compressor is operating in low stage the 24v DC compressor solenoid coil is de-energized. When the compressor is operating in high stage, the 24v DC solenoid coil is energized. The solenoid plug harness that is connected to the compressor HAS an internal rectifier that converts the 24v DC signal to 24v AC. DO

NOT INSTALL A PLUG WITHOUT AN INTERNAL RECTIFIER.

Unloader Test Procedure

The unloader is the compressor internal mechanism, controlled by the DC solenoid, that modulates between high and low stage. If it is suspected that the unloader is not working, the following methods may be used to verify operation.

1.Operate the system and measure compressor amperage. Cycle the unloader on and off at 30 second plus intervals at the User Interface (from low to high stage and back to low stage). Wait 5 seconds after staging to high before taking a reading. The compressor amperage should go up or down at least 20 percent.

25HPA6

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Contents Electrical Shock Hazard Safety ConsiderationsUnit Operation and Safety Hazard Indoor Thermostat Control OptionsUnpack Unit Install on a Solid, Level Mounting PadCheck Equipment and Job Site Clearance RequirementsOutdoor Unit Connected to Factory-Approved Indoor Operating AmbientElevate Unit Make Piping ConnectionsLiquid Rated Vapor Unit Size Accessory UsageMake Electrical Connections Airflow Selections ECM Furnaces Compressor Crankcase HeaterSystem Functions And Sequence Of Operation Install AccessoriesStart-Up Compressor Operation Time DelaysDefrost Hold Liquid-Line Solenoid AccessoryInfinity Controlled low ambient cooling DefrostCheck Charge Unloader Test Procedure Pressure Switch ProtectionControl Fault 230V Line Power Disconnect DetectionThermistor Sensor Comparison Temperature ThermistorsFailed Thermistor Default Operation Status Codes TroubleshootingEdge Thermidistat Models TP-PRH-01 or TP-NRH-01 Puronr R-410A Refrigerant Quick Reference Guide Care and MaintenanceFinal Checks Catalog No 25HPA6---1SI