Do you have a multimeter and if so, do you know how to use it?
Step 1, check all fuses.
Step 2, check for voltage at the heater. You should have 240V across the terminals when the heater is calling for heat. If not, then you probably have a bad relay, go to step 4.
Step 3, if you do have 240V at the heater, disconnect the power, then disconnect the heater and set your multimeter on ohms and check the heater. A good heater should read between 9-14 ohms. any more or less, than you have a bad heater.
Step 4, If the heater is good or you did not have 240 at the heater terminals, turn the power back on and check the output at the relays, You should have 120V on each relay between the white neutral wire and the relay and 240V between the 2 relays when the tub is calling for heat. If not, you have a bad relay.
Relays can be replaced for about $15 each from Amazon. If you are able to solder, you can replace them yourself, if you can't, an electronics repair place can replace them. I recommend if replacing the relays, to replace all of them to refresh the board, so to speak.
