Checking the Display Messages
The first area to chec k when troubleshoo ting the 17/19EX is the LID display. I f the alarm light
is flashing, check the pr i mary and secondary m es s ag e lines on the LID default screen (Figure
14). These messages wi ll in dicate where the fau lt is occurring. The Alarm His t ory table on the
LID Service menu will also carry an alarm message to further expand on this alarm. For a
complete listing of messages, see Table 8. If the alarm light start s to f las h while accessing a
menu screen, depress EXIT to return to the Default screen to read the failure message. The
compressor wil l not run with an alarm co ndition existing, unless the alarm type is an
unauthorized start or a failure to shut down.
Checking Temper a t ur e Sen sor s
All temperature sens or s ar e of the thermistor type. Thi s means that the resistan ce of the
sensor varies with temperature. All sensors have the same resistance characteristics.
Determine sens or temperature by measuring vo ltage drop if the controls are powered, or
resistance if the cont rols are powered of f. Compare the reading s to the values listed in Table 9A
or Table 9B.