Pentair Pool Products MiniMax NT Series Service Manual page 40

Troubleshooting
1. The primary responsibility for the SERVICE Light is to illuminate whenever there is a problem
that prevents the heater from firing (please see Diagnostic Lights explanation at the beginning of
this section). However, it will also be ON during the Fan 15-second pre-purge and the 40-second
Hot Surface Igniter heat up.
2. The SERVICE Light also comes ON if the burners do not continue to burn properly or if the
flame goes out, if there is a bad Flame Sensor or Flame Sensor wire or if anything else causes the
Ignition Module to restart the ignition sequence. So, if the SERVICE Light comes ON and heater
stops firing and then the heater fires and the SERVICE Light goes out, simulating a Rapid Cycle,
it can be caused by a loss of or weak signal to the Ignition Module by the Flame Sensor.
3. The SERVICE Light will come ON if the water temperature in the Inlet side of the Header
reaches 115 degrees or if the water temperature at the outlet of the heat exchanger reaches 150
degrees. If the heater is cycling in this mode, the three green lights on the back of the Control
Board will flash OFF and ON as the heater shuts down and refires.
If a weak Flame Sensor signal causes the cycling, the SERVICE Light will go ON and OFF, but
the High Limit Light will remain ON. If water temperature causes the cycling, the SERVICE Light
will go ON and OFF AND the High Limit will go ON and OFF as well.
OUT RETURN
POOL
POTENTIOMETER
Figure 36.
P/N NTSM03
NOTE
24 VAC PRESS HILMT TFUSE
MODEL 6800
ELECTRONIC THERMOSTAT
TPROBE
SPA COM POOL
FRONT PANEL
POOL / OFF/SPA
THERMOSTAT SELECT SWITCH
THE SERVICE LIGHT
VALVE IGNITION MOD
SPA
POTENTIOMETER
40
PVALV LED
TFUSE LED
HITEMP LED
Rev. B 2-11-04