I have a Jacuzzi Caressa Moel# 878000. I don't know the age, it was given to us last year because it did not work. I put a new heater in it last year, used it all summer and into the fall. I drained it and cleared all the water from all of the lines. When I refilled it last week I started the jets and they worked fine, I let them run about 10 minutes and then pushed the airbutton to the heater mode. (This is a 110 unit that only heats when the jets are off and the pump is on a lower speed.) The heater comes on momentarily (1 or 2 seconds) and then kicks off. I suspect the heater kicks off because there is no flow from the pump. I do not know what inside the control module is supposed to happen to shift the pump to the lower speed, I am sure the pump is not on though. The only name on the control module door is Jacuzzi, there are no electronics inside though, this is an old unit.
I have a service man scheduled to come out in a couple of weeks, he told me I need to bleed the lines, my thinking is that the jets are pushing a lot water and his train of thought makes me think I need another service man, who is right?? Can you tell me what to look for ?

You probably have this fixed already, but I would have to ask what is kicking off... GFI breaker? High limit switch? If high limit, then there isn't enough water flow. If the GFI breaker, you will have a bad element. If you know for sure your pump is staying on high speed, you could have a stuck contactor on the pump. This would also cause the GFI to trip due to over current... can't run high speed and heat at the same time.