No heat with Rapid Heat U395000 Jacuzzi jetted tub

If you still have your old heater do a ohms reading if you are getting the corect reading it might of not be the heater that went bad both the t-stat sensor and high limit can cause no heat.But in most cases if the heater is good an still no heat it a power issue if the reset has been reset also if not heating from the low speed from your pump an is using a circ pump make sure that its still good cause u can hit the reset an it will start to heat but the tripp again a minute later. But first start at the powr going into the spa at the heater term on the circuit board then move on from there u might get power going into the spa but the on n off relay on the board could of went so then look for power at the heater if u have power at the board but no power at the heater then most likely its the board that went bad if no power at the board make sure your 30amp breaker is still good cause alot of 30amp gfci breaker especialy seimens can burn up an then it will not send the power from the house into the shut off box to the spa.The other cause for no power at the board could be the result of a bad main topside controls they tend to use cheap ribbon cable that go bad you will still get a heat indicator light come on but the topside controls will not send the singal to the board to turn on the heat even the mainn controls have a little circuit board that relays imfo to the main circuit board also mice love to eat the ribbon cables an one tiny tear can cause this to happen good luck If you still have your old heater do a ohms reading if you are getting the corect reading it might of not be the heater that went bad both the t-stat sensor and high limit can cause no heat.But in most cases if the heater is good an still no heat it a power issue if the reset has been reset also if not heating from the low speed from your pump an is using a circ pump make sure that its still good cause u can hit the reset an it will start to heat but the tripp again a minute later. But first start at the powr going into the spa at the heater term on the circuit board then move on from there u might get power going into the spa but the on n off relay on the board could of went so then look for power at the heater if u have power at the board but no power at the heater then most likely its the board that went bad if no power at the board make sure your 30amp breaker is still good cause alot of 30amp gfci breaker especialy seimens can burn up an then it will not send the power from the house into the shut off box to the spa.The other cause for no power at the board could be the result of a bad main topside controls they tend to use cheap ribbon cable that go bad you will still get a heat indicator light come on but the topside controls will not send the singal to the board to turn on the heat even the mainn controls have a little circuit board that relays imfo to the main circuit board also mice love to eat the ribbon cables an one tiny tear can cause this to happen good luck