Ation; Compressor Operation, Checkout And Status / Error Codes - Lennox XC20-036-230-01 Installation And Service Procedure

High and Low Pressure Switch Errors
Table 10. Outdoor Control 7-Segment Display Alert Codes - High and Low Pressure Switches
System fault and lockout codes take precedence over system status codes (cooling, heating operating percentages or defrost/dehumidification). Only
the latest active fault or lockout codes are displayed (if present). If no fault or lockout codes are active, then system status codes are displayed. Alert
codes are also displayed on the iComfort Wi-Fi
Alert
Priority
Codes
The outdoor unit cycled off due to
E 410 Moderate
low pressure switch opening.
The low pressure switch has
opened 5 times within one hour. As
E 411 Critical
a result, the outdoor unit is locked
out
The outdoor unit high pressure
E 412 Moderate
switch has opened.
The high pressure switch has
opened 5 times within one hour. As
a result, the outdoor unit is locked
out
E 413 Critical
NOTE - Unused on XC20. Used for
heat pump applications only.

Compressor Operation, Checkout and Status / Error Codes

OPERATION:
The compressor is a 380VAC three-phase variable-capacity scroll compressor that is approved for use with HFC­410A refri­
gerant. The compressor, when connected to an inverter, is capable of operating in a running frequency range from 22 hertz
up to a maximum of 70 Hertz (maximum hertz is dependent on compressor size). The compressor speed is determined by
demand from the room thermostat.
CHECKOUT:
Figure 33. Compressor Operation, Checkout and Status/Error Codes
IMPORTANT: If compressor replacement is required, remove the compressor through the top of the unit. Removal through
the access panel is not possible.
XC20
®
thermostat.
Alarm Description
.
.
Possible Causes and Clearing Alarm
Unit pressure is below the lower limit. The system is shutdown. The low pressure
switch closes above 90PSIG and opens below 40PSIG. Confirm that the system is
properly charged with refrigerant. Check TXV, indoor unit blower motor, dirty filters
or clogged refrigerant filter. Confirm that the evaporator coil is clean. The alarm
clears after the pressure switch opens or after a power reset.
Low pressure switch error count reached 5 strikes. The low pressure switch for
HFC­410A opens at 40PSIG and resets at 90PSIG. Confirm that the system is prop­
erly charged with refrigerant. Check for clogged TXV, blockage to indoor unit blower
motor, dirty filters or clogged refrigerant filter. Confirm that the evaporator coil is
clean. The alarm clears after a power reset.
Unit pressure is above the upper limit. System is shut down. The high pressure
switch opens at 590PSIG and closes at 418PSIG. Confirm that the system is prop­
erly charged with refrigerant. Check for clogged TXV, blockage to indoor unit blower
motor, clogged refrigerant filter. Confirm that the outdoor unit is clean. The alarm
clears after the pressure switch closes or a power reset.
For heating, indoor CFM may be set too low. For zoning system, zone CFM may be
set too low.
Open high pressure switch error count reached 5 strikes. System is shut down. The
high pressure switch for HFC­410A will open at 590PSIG and close at 418PSIG.
Confirm that the system is properly charged with refrigerant. Check condenser fan
motor, clogged TXV, blockage to indoor unit blower motor, stuck reversing valve or
clogged refrigerant filter. Confirm that the outdoor unit is clean. The alarm clears
after a power reset.
For heating, indoor CFM may be set too low. For zoning system, zone CFM may be
set too low.
56
0.657 0.657 0.657
0.657
0.657
0.657
0.723 0.723 0.723
0.587 0.587
0.587