I have a no-name brand spa the uses Balboa controls. It is an older M7 with a pleasure switch on the heater assembly. It heats all of the time.
Here are the symptoms of the problem: starting with a tub temp below the heater turn on point, turn on the power 220 VAC to the tub and the tub heats normally. I have the temp set at 100 degrees. When the tub temp indicates 101 for a bit, the heater light goes out and the pump continues to run. All is normal up to this point. But instead of the pump shutting off after it cools the heater, it continues to run and it continues to heat (with the heat light OFF). After a while the temp gets to about 107 degrees and OH error occurs as you would expect. The tub is now shut down. The only way to restore it is to power cycle the 220 VAC. It seems to me that the M7 controller is basically functional with the exception that the heater never really shuts off even though the controller tells it to (heat light OFF).
What I have done: The tub is about 5 years old so decided to do some maintenance while troubleshooting the problem. I have replaced the heater assembly (Over temp probe, heater element and pleasure switch) and the Temp probe into the tub. I have rebuilt the heater pump. I am running it without any filters to eliminate flow as a problem.
Are there any relays on the M7 controller that could be welded shut? Other solid state switchs that could be shorted? Do you have any suggestions? My next step will be to replace the controller board.
Thanks ahead of time for your assistance.
