286A / 288A
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, VR and L2 on 286A models and VS and L2 on 288A models (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
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.
286A Models - Compressor Thermal Cutout
The control senses the compressor voltage at VR and VS. When starting or running, a phase difference of the voltages on the inputs will indicate the thermal protector is closed. If the phase difference is 5_ or less for 10 seconds, the internal protector is open. The control
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.
288A Compressor Thermal Cutout
If the control senses the compressor voltage after
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.
Low or High Contactor Open (286A models) / No 230V at Compressor Contactor (288A models)
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.
286A Models Only - Compressor Start Detection on Models with Bristol Compressors Only
In low stage, if the specified start voltage at VR terminal is not achieved, the start relay is
In high stage, if the specified start voltage at VS terminal is not achieved, the start relay is
If the specified start voltage is not achieved for 3 consecutive low stage starts, low stage operation is locked out for 30 minutes. If the specified start voltage is not achieved for 3 consecutive high stage starts, high stage operation is locked out for 30 minutes. The control will flash the appropriate fault code.
Troubleshooting 286A units for proper switching between low & high stages
Check the suction and liquid pressures at the service valves. Suction pressure should be reduced by
Troubleshooting 288A units for proper switching between low & high stages
Check the suction pressures at the service valves. Suction pressure should be reduced by
NOTE: The liquid pressures are very similar between low and high stage operation, so liquid pressure should not be used for troubleshooting.
Compressor current should increase
When the compressor is operating in low stage the 24v DC compressor solenoid coil is
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 UI (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 per- cent.
2.If the expected result is not achieved, remove the solenoid plug from the compressor and with the unit running and the UI calling for high stage, test the voltage output at the plug with a DC voltmeter. The reading should be 24 volts DC.
3.If the correct DC voltage is at the control circuit molded plug, measure the compressor unloader coil resistance. The resistance should be 32 to 60 ohms depending on com- pressor temperature. If the coil resistance is infinite, much lower than 32 ohms, or is grounded, the compressor must be replaced.
Temperature Thermistors
Thermistors are electronic devices which sense temperature. As the temperature increases, the resistance decreases. Thermistors are used to sense outdoor air (OAT) and coil temperature (OCT). Refer to Fig. 7 for resistance values versus temperature.
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