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garrygoeson
garrygoeson, Home Appliance Technician
Category: Pool and Spa
Satisfied Customers: 469
Experience:  Over 27 years Repairing Pool & Spa Equipment,Gas Heaters,& Whirlpool Bath Tubs. Certified by many Pool & Spa Manufacturers.
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I have an old (1995) Blue Falls hot tub with Balboa circuit

Customer Question

I have an old (1995) Blue Falls hot tub with Balboa circuit board. It had been working well, but had been left for a week while we were away. When I turn on the breaker, nothing works and error message is Sn. I disconnected the heater and got the same message. I have replaced the temp & high limit sensor harness. No change. I tried to run it with no filter in place. No change. The water in the tub is cold, as is the water in the heater. I bypassed the circuit board to test the pump. It runs on both high and low. I checked the fuses out of the board with a continuity tester, and checked them wrapped in tin foil in the board. They check out ok. I removed the circuit board to check for visible damage and found none. When I replaced it, the error message came up as Sn and then switched to flashing OH. Any help?
JA: Who manufactured the hot tub?
Customer: Blue Falls for Arctic Spa.
JA: Do you plan on doing the work yourself?
Customer: Yes, we are 3 hours from the nearest service centre.
JA: Anything else we should know to help you best?
Customer: Can't think of anything. The water we use comes from a well, but it is well filtered and treated. We do get some mineral buildup.
Submitted: 3 months ago.
Category: Pool and Spa
Expert:  garrygoeson replied 3 months ago.

Hi Anne:

My name is Garry. I'll be glad to assist you with your spa.

Expert:  garrygoeson replied 3 months ago.

Since your replaced the Temp & Hi-limit sensors, (I'm assuming they're both new), There is a way to test them, and if they both test good, then, I'm very sorry to say , you may have a faulty circuit board. Very first thing to try is to disconnect power to the spa, remove the connector from the Hi-limit/Temp Sensor set from the circuit board. Very carefully clean the pins on the board from any dirt or corrosion that may be present.

Plug the sensors back into the board and power the spa back on. If you are still getting the fault code(s), let me know, and we can go into testing the sensors. Thank you.

Customer: replied 3 months ago.
We have also disconnected the heater and it seems to have calcium buildup inside the heater tube. Could this be a problem for the high limit sensor?
We did not see any dirt or corrosion on the circuit board when we had it out.
We will not be able to test the sensors until next Friday when we will return to the cabin.
Expert:  garrygoeson replied 3 months ago.

If there is a large build up inside the heater area, there could be a possibility it may cause an improper transfer of heat, possibly allowing for problems with the hi-limit sensor. Although, in my experience I have not come across this issue.

When I was referring to corrosion, I meant specifically the pins on the board where the sensors connect to, not the entire board.

When you are ready, I can post the steps for testing the temp/hi-limit sensors.

Customer: replied 3 months ago.
We have cleaned the heater and are still getting the Sn code. It is not likely a problem with the sensors, since we replaced them. Any ideas?
Expert:  garrygoeson replied 3 months ago.

If you are absolutely certain the sensors are good, and you are still getting the "Sn" fault code, the next likely suspect is the circuit board.

When the sensors are working properly they will have a specific resistance, (measured in Kilo-ohms), that will compare to a specific water temperature, (measured in degrees F), as determined by a chart from Balboa. If this resistance is proper, and the board is not reading it, then you will get the "Sn" code. Unfortunately, the only way to solve this problem is to replace the circuit board.

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