
Page 66
31-5000751 Rev. 0
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
communicating thermostat.
GF= Gas Furnace, AH=Air Handler, ID=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OD=Outdoor Unit (AC or HP), ZA=Zone system and TS=Thermostat
Alert
Code
Inverter
Flash
Code
Priority
Condition
Actual Displayed
Alert Text
Component or System Operational State and Troubleshooting Tip
How to Clear Alert
Code
422
Service
Soon
OD Compressor
Top Cap Switch
Open
Compressor top cap switch exceeding thermal limit.
•
Check condenser fan motor, TXV and indoor unit blower motor.
•
Check for stuck reversing valve or clogged refrigerant filter.
•
Check to ensure that one of the wires from the top cap switch has not been
disconnected from one of the
TP
terminals on the outdoor control. Reconnect
wire if disconnected.
•
Check superheat and sub-cooling.
Automatically
clears when error
is corrected.
442
Service
Urgent
OD Compressor
Top Cap Switch
Strikes Lockout
The top cap switch has opened five times within one hour. As a result, the
outdoor unit is locked out.
•
This condition occurs when compressor thermal protection sensor opens five
times within one hour.
•
Outdoor unit will stop.
To clear, discon
-
nect power to
outdoor unit and
restart.
Table 20. Outdoor Control 7-Segment Display Alert Codes - Top Cap Switch
Reactor Operations, Checkout and Status / Error Codes
OPERATION:
Reactor (Inductor or choke) is a passive two-terminal electrical component that stores energy in its magnetic field. Reactors
are one of the basic components used in electronics where current and voltage change with time, due to the ability of
inductors to delay and reshape alternating currents.
CHECKOUT:
Main Power ON – Voltage IN reactor should be the same as the voltage OUT. With main power OFF and reactor disconnected
from system; resistance between leads should be the same
STATUS CODES:
None
ERROR CODES:
None
VOLTAGE “IN”
VOLTAGE “OUT”
FIGURE 39. Reactor
Outdoor Fan Operation and Checkout
OPERATION:
The NS18HM units have a variable speed ECM fan motor. The variable speed ECM fan motor is controlled by PWM fan
output when the compressor is running and will vary the fan speed to match the compressor capacity.