Pool and Spa
Questions about Pool Repair? Ask an Expert Online.
My name is Garry. I'll be glad to assist you with your spa.
Since you started getting the flashing "FL1" code, and then replaced the flow switch, only to still be getting the code, it's unlikely not a problem with the switch. If you look at the flow switch,(located in the plumbing near the top of the heater), you should be able to see a little "flag" inside the switch. When water is flowing through the switch, the little "flag" will then be pushed to a post next to it.
When the spa is trying to heat, and you do not see this "flag" next to the post, this will confirm there is insufficient or no water moving through the switch. You should have a Circulation pump, in addition to the two larger jet pumps. This circulation pump is the pump that MUST run to move water through the heater and flow switch. You may find it mounted behind the Control Box. If the two other pumps run, neither of these pumps have anything to do with your spa heating.
Locate the Circ pump, (it will be much smaller in size than the two Jet pumps), and let me know what you find. Post your findings here when you are ready, and I'll respond back when I sign on again. Thank you.