Jacuzzi Z Builder Series Mechanics And Repair page 47

If you have proper voltage, double check the fuses inside the control box. You do
this with power OFF and the meter set to ohms.
Finally, with proper power to the spa and the all fuses are OK, the only possible
reason for failure is either the transformer or the board. Most of the spas have a
separate transformer. In very, very rare occasions the failure is the transformer. I
12 years of working on these electronic spas, I can't remember one spa's failure
attributed to the transformer. It COULD be the problem but likely not. So that
leaves the failure the board. This unfortunately isn't rare. Often caused by line
wire surges and brownouts. It can also be caused by lighting. Although the board
failure is not common, it can fail. You need to replace.
#1 CLICK and then nothing.
The spa does #1 CLICK it goes into the self test. If you don't get to the #2 CLICK,
it could be one of several reasons. First and least likely is also a board failure.
Likely the failure is one of the sensors. See the ERROR codes section. But let
me mention the failures that can occur here in case the ERROR doesn't display
either in Digital readout or on some ECHO spas, the heater light flashes.
The spa board at this point is looking at the sensors. One sensor it looks at is the
pressure or flow switch. The board is expecting to see an OPEN pressure or flow
switch. OPEN tells the board it will see a CLOSED sensor when the pump is
turned on. If the board doesn't see this sensor OPEN, it will not go further.
The board also checks the temperature and overheat sensor. It compares the
temperatures and also if they are within tolerance. IF so, they pass. Then the
board considers the pressure/flow switch. The board must find either in the OPEN
condition. If the topside goes to solid FL or FLO or the heater light starts flashing,
it indicates the switch has failed.
It's easy to check if the pressure switch has caused the failure. Unplug one or
both wires of the pressure/flow switch from the board. IF the pressure/flow switch
has failed and you unplug it, the pump will come on. If it does not, then it's not the
pressure switch