Manual

Testing the Sensor Set

6. Within a minute or so, see if the same or other sensor is

now reading consistently higher:

If the same sensor (A vs B or t vs H) is reading higher UÊ

after the sensor interchange, the problem is on the

circuit board. Replace the circuit board.

If the opposite sensor is now reading higher, the problem UÊ

is with the sensor(s). Replace the sensor set.

*If you wait more than 2 minutes after plugging the

sensors back in, heating may start (even outside a ﬁlter

in Economy or Sleep mode) due to a stray Cd/CLd/COLD

WATER condition usually detected when sensors are

being plugged in while the system is running.

7. If there is a message indicating an open or faulty sensor:

Unplug the sensor set (but leave the original sensors UÊ

in the heater) and plug in the test sensor set. Put both

sensors into the same cup of warm water (ideally above

the set temperature, so the spa won't try to heat during

this test, as there is no heater protection during this

test) and verify that they read the same temperature

(within 1°F/0.5°C).

If the problem is solved, replace the sensor set. If the UÊ

problem is not solved, do not replace the sensor set.

Plug in the original sensor set to verify that there is not a UÊ

connection problem.

If the problem continues after following the above steps, UÊ

then replace the circuit board.

1. Check sensor wires for cracks or damage that may

indicate the presence of a rodent.

2. Inspect the connections of both sensors on the circuit

board. The plugs must be clean.

3. If the sensors are not totally failing but are showing

excessive (2° F/1.0 °C or more) difference between the

two sensors when not heating (a possible cause of

Sn/SnS/SENSOR SYNC, HL/HFL/HTR FLOW LOW, and

LF/LOW/FLOW/messages), do the following:

Note which sensor is reading consistently higher UÊ

(A vs B or t vs H).

4. Unplug the two sensors from the circuit board and

exchange their positions (i.e., plug the one that was in

the “Sen. A” jack into the “Sen. B” jack and vice versa).

5. Press a panel button if any "stray" faults appeared

during the process. (Stray faults are normal when

sensors are unplugged then plugged back in while the

system is running.)