As a safety feature the heater will not work if there is a flo error. So I will consider that is not a seperate issue.
The following is quoted from the users manual:A flashing “FL1” display means the flow switch is
malfunctioning open, the filter cartridge is excessively dirty or an “air lock” condition has occurred at the circulation pump intake...
To correct condition perform the following:
1. Verify water level is above all jets but below lowest pillow. Add water if necessary.
2. Check for clogged or dirty filter cartridge (sec. 12.1, page 30).
3. Purge “air lock” from circulation pump intake by removing filter cartridge. Hold your garden hose over the filter cartridge wall fitting while using a rag as a seal around hose end. Ask a helper to turn on water for 30 seconds, then turn off. Reinstall filter cartridge and check spa (sec. 12.1, page 30).
4. If the circulation pump is not running, turn power off at the main breaker, then turn power back on. This will reset the circulation pump priming cycle. Once the pump is primed, the error should clear.
5. If problem persists, contact your authorized Jacuzzi dealer.
I have also seen this error after a flow switch replacement due to an obstruction in the end of the flow switch itself, ie. a piece of silicone, sand, tiny rock, etc. A good tech would have only left the job unfixed after explaining to you why he is unable to fix it.
If it was working when he left then it can probably be fixed by following the steps above.
If this did not help you, please supply more information.
1. Is the error constant or does it come and go.
2. Did the repair guy give you the old part or let you look at it.
3. Did you try ALL of the steps listed above?
4. How old is the spa?
Unfortunately this is the best I can do without access to your spa.
RobertB