Pentair MiniMax Plus Service Manual page 24

Troubleshooting
This list will suggest situations that might cause
this symptom.
1. Check water temperature - if the water has
reached the desired temperature, the thermostat
will cut off power to the module and the heater
will stop firing. In this case the "Power" Light
would remain "ON".
2. Check the voltage on both sides of the
transformer - there should be 24VAC on the
secondary side to enable the controls to operate.
If the voltage is less than required, there is
probably a wiring short or the transformer has
been incorrectly wired on the primary or supply
side. Because the Power Light is not a specific
24VAC light, it will illuminate with less than
24VAC, so even if we see a power light we
cannot assume that correct voltage is present.
3. The Pool/Spa switch may have inadvertently
been switched "OFF" - even though the Pool/
Spa switch does not have to be ON for the
Power Light to be ON, it does have to be pushed
to either the Pool or Spa position in order to
transfer the voltage to the rest of the controls.
P/N 38033
DIAGNOSTIC LIGHTS SHOW
"POWER" ONLY!
4. Make sure the Thermostat knobs have been
turned to "Hot" - because the voltage must pass
through the thermostat (potentiometer) first
before going to any other control, if the
potentiometers or thermistor is not working or
disconnected from the circuit board, only the
Power Light will be on. If you suspect this may
be the problem, first check the thermistor
connections on the back of the circuit board,
(replace thermistor if necessary) and if you still
only see the power light attach a jumper wire
across the connections on the potentiometer.
When voltage passes through the thermostat
circuit (potentiometer/thermistor), whether by
normal operation or by jumper wire, the
"T"STAT Light will come On.
5. If there is a "Remote" switch or control attached
to the heater, make sure that it has been switched
to "ON" or change it to manual operation. To
be absolutely sure the Remote is not keeping
the heater off, disconnect the remote wires from
the back of the circuit board and attach a jumper
across the two terminals.
6. Last, but not least - check the wiring diagram
to see if all the wires are connected to the correct
control terminals.
2 4
Rev. C 12-1-00