hi i bought used older master spa model number de-mas 500-dcah on circuit panel when we connected it up to 240 volts it had red lihgt come on beside d5 was hoping someone could help me out spa is not heating,jets work fine.
thank you

post some photos of this equipment and someone will be able to help you better.

Otherwise, I'd check the continuity and voltage delivered to the heater element.

have no heat. two wires appear to be burnt coming out of one of the conector boxes. what would cause this and what would i have to replace?