Lennox XC25 – 7-Segment Alert and System Status Codes

Alert codes are displayed using the 7-segment display loc­ated on the outdoor control.

NOTE – System fault and lockout codes take precedence over system status codes (cooling, heating operating per­centages or defrost/dehumidification).

The 7-segment will display an abnormal condition (error code) when detected in the system. A list of the codes are shown in table 6.

Alert codes can be reset manually or automatically:
1. Manual Reset
Manual reset can be achieved by one of the following methods:

• Disconnecting R wire from the outdoor control R terminal.
• Turning the indoor unit off and back on again

After power up, all currently displayed codes are cleared.

2. Automatic Reset
After an alert is detected, the outdoor control continues to monitor the unit’s system and compressor opera­tions. When/if conditions return to normal, the alert code is turned off automatically.

NOTE – Error codes can be recalled by following in­ formation shown in the table on page 37.

The field test mode allows the unit to be put into diagnostic mode and allows the installer to perform multiple tests on the control / unit.

Diagnostic Mode
Diagnostic mode is only available when the system is idle or during an active / suspended call for heating or cooling. Diagnostic mode is terminated when the exit command is given, the button is pressed and released without entering the diagnostic menu or 10 minutes has passed, whichever comes first.

When this mode is selected all installed temperature sensor valves (non-open and non-short) are shown on the 7-segment display. The following system status codes are displayed:
– Cooling
– Percentage demand operation
– Outdoor fan RPM
– Active error codes

Outdoor Fan Mode
Diagnostic mode is only available while the system is in idle mode. This mode can be exited with the proper command or after 10 minutes has passed.

In diagnostic mode, the control ,energizes the outdoor fan at the highest speed. The control continuously displays the fan RPM on the 7-segment display.

1. Turn room thermostat OFF.
2. Install a set of refrigerant gauges on the system to monitor the pressure.

NOTE – All operation monitoring devices: High pressure switch, low pressure switch and compressor internal vacu­um protection remain active in the system. This will prevent the compressor from recovering all the system refrigerant into the outdoor unit.

NOTE – If the pump down jumper is in the ON position dur­ing power-up, it is ignored.

3. Move the Pump Down jumper (page 26 for location) from the OFF position to the ON position.

4. Shut off the liquid line service valve to stop the flow of refrigerant into the indoor coil.

5. After a three-second delay, the compressor and out­ door fan will ramp up to 100% capacity. (Indoor fan will remain OFF.)

6. Monitor the low-side pressure at the outdoor unit. The internal vacuum protection in the compressor and/or one of the pressure switches prevents full recovery of the refrigerant into the outdoor unit. When the system reaches this condition, the suction line service valve should be shut off and the Pump Down Jumper moved back to the OFF position.

NOTE – The outdoor control will stay in pump down mode for five minutes, after which the outdoor control initiates a compressor shutdown sequence.

7. Use a refrigerant recovery machine to recover the re­maining refrigerant on the indoor side of the system.




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