I have an older streamline spa with balboa control. It has 2 pumps and one blower. It is wired 220v, brand new 50 amp electrical service to tub. Problem is when the jet pump(s) are running,after about 20 minutes the GFCI trips and upon resetting the breaker, the tub has a 3 second countdown to start. When it restarts the blower motor comes on for a second and the breaker trips again, the tub remains completely shutdown for about 1/2 hour then it will run. If i don't run the jet pump(s), the breaker does not trip within 20 minutes, however, the breaker will trip hours later when the tub is not being used. I disconnected one wire at a time to get the tub to start, and with the blowers white neutral wire disconnected the tub starts and the breaker has not tripped since, but the blower does not work now. Also, the temp sensor i will be replacing as the water does not reach displayed temp, it stays 6 degrees cooler than set temp. The heater is new. So, is the blower motor bad or is there something I'm overlooking?

Most often when a tub begins a filtration cycle it activates the blower for 30 seconds in order to agitate the water...most likely this is when your breaker is popping and it is most likely due to a bad blower.