I have recently purchased a 1997 Coast Spa that runs fine except for an error code that keeps showing up on the key pad. It reads FL C
The tub completely shuts down when this appears, the pump stops and the temperature drops. Everything goes right back to normal if you hit any button on the control panel (even if you just turn the light on, the pump kicks back on and it starts heating up again).

Normally, FLC means Flow Switch Close. The only thing you have to do is to change the pressure switch. You can try also to adjust it. Here's a picture that can help you a little bit.

http://www.poolspahelp.com/images/Press ... ch%203.gif