No Heat 97 Cal Spa

I have a 97 Cal Spa that is not heating at all. The pump is working fine. Where to start? I have drained the tub, but want to repair it for this winter.

Well the first thing I would try is to remove the filter and run the pump with the thermostat turned up to see if you get a heat call. Unfortunately the spa will need to be filled to do this and there must be nothing floating in the water that could get sucked into the filter system. Sometimes filters will look clean but can get clogged with body oils and lotions and prevent proper water flow to go through the heater cauing it not to come on.

I did do this before I drained it. Sorry, I should have mentioned that. I do keep the filter clean and the water was circulating fine.

I did that before I drained the tub. Sorry, I should have mentioned that. I have good flow through all the jets and good suction at the suction ports. I could feel water going through the heat tube, but there was no heat coming from the heat tube. There was no heat at all. I had not used the tub for 2 weeks. The temp had gone down to 70 and continued to go down as I monitored it over the next couple of days.

Ok, does your spa have an indicator of some sort that will come on when the heater should be on. If so does that indicator come on when you turn up the thermostat? If it does we need to verify that the circuit board is suppling power to the heater. If it is then your heater is probably bad. If not it could be the board. If you are not getting the indicator to come on when raising the temp then the problem lies else where but need to know this information first.