Top Cap Switch Operation, Checkout And Status / Error Codes; Outdoor Control 7-Segment Display Alert Codes - Top Cap Switch - Lennox XP25-024-230-01 Installation And Service Procedure

Top Cap Switch Operation, Checkout and Status / Error Codes

OPERATION:
Some units are equipped with a compressor-mounted normally closed temperature switch that prevents compressor damage
due to overheating caused by internal friction. The switch is located on top of the compressor casing. This switch senses the
compressor casing temperature and opens at 239-257°F to shut off compressor operation. The auto-reset switch closes
when the compressor casing temperature falls to 151-187°F, and the compressor is re-energized. This single-pole,
single-throw (SPST) bi-metallic switch.
COMPRESSOR TOP CAP SWITCH
CHECKOUT:
Using a multimeter set to ohms, with the terminals disconnected from the system, check the resistance between the two
terminals of the top cap switch. If the resistance reading is 0 ohms, the switch is closed.
STATUS:
None
ERROR:
Table 15. Outdoor Control 7-Segment Display Alert Codes - Top Cap Switch
NOTE - 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
Compressor top cap switch ex­
E 422 Moderate
ceeding thermal limit.
The top cap switch has opened 5
times within one hour. As a result,
E 442 Critical
the outdoor unit is locked out
(SPST BI-METALLIC SWITCH,
NORMALLY OPENS AT 239-257ºF,
AND CLOSES AT 151-187ºF
SWITCH COVER
Figure 49. Top Cap Thermal Sensor Switch Operation
Figure 50. Top Cap Thermal Sensor Switch Checkout (S173)
®
thermostat.
Alarm Description
.
TOP OF COMPRESS0R
Possible Causes and Clearing Alarm
Check condenser fan motor, TEV, indoor unit blower motor, stuck reversing valve,
clogged refrigerant filter or undercharge. When error occurs with inverter slowdown
errors, check for system overcharge. Automatically clears when error is corrected.
When compressor thermal protection sensor opens 5 times within 1 hour, outdoor stops
working. To clear, disconnect power to outdoor unit and restart.
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