You walk out to use your spa or hot tub and immediately you know something is wrong. Either the water is cold, which makes for a less than enjoyable soak or nothing is working at all. The spa appears dead.
If you have a digital system in your spa or hot tub with a digital upper control, you first look at the upper control display to see if it will tell you what is going on. Looking at your upper control, you see abbreviations like SN1 or FLO or even “—-“. What do these symbols and abbreviations mean?
The symbols and abbreviations displayed on your spas upper control are called error codes. They tell you that the spa has detected a situation for which it then tries to identify. Different equipment manufacturers use different codes to identify certain conditions found by the spa self diagnostic system.
We will look at the two spa systems I receive most questions about. Balboa controls and Sundance Spas controls.
Balboa, one of the most common spa controls manufacturers, uses the following codes.
pd = Power supply, unit running on battery backup
OH = Sensors reading 112-118 Degrees
Flo = Improper flow or pressure switch malfunction
Cool = Water temp 20 degrees below set point
ICE = Potential freeze condition has been detected
Sn1 = Hi-limit sensor malfunction
Sn3 = Temp sensor malfunction
LOC = Interlock failure – possible pump or ozone spike
(—-) = Unknown water temperature. (Displays when Spa is first powered up after refill).
Sundance Spa, one of the largest spa manufacturers, uses the following error codes.
ILOC = Interlock failure – possible pump or ozone spike
FLO = Pressure switch malfunction or Flow switch malfunction (system specific).
Hold = Flow Switch (heater is deactivated. Pump may also be deactivated).
Hold = Panel buttons pressed to many times to quickly.
HOT = PCB temperature above acceptable limit – air blower on.
ICE = Potential freeze condition.
PnL = Communication between the panel and circuit board is faulty.
(—-) = “WATCHDOG” (spa is deactivated) A problem has been detected. (system can not identify)
Sn1 = OPEN SENSOR (heater is deactivated) or SHORTED SENSOR (spa is deactivated).
Sn3 = OPEN SENSOR OR SHORTED SENSOR ( heater disabled).
(This is not a complete list and your spa error codes may vary depending on year and model.)
Notice the similarities and differences in the codes. Both use FLO,SN1,SN3 and ICE and so forth, Differences include, (—-). Meaning totally different things between the two systems. You must use the error codes for your control system to accurately diagnose the problem with your spa.
Lets take a quick look at the FLO error code. Both manufacturers state FLO is caused when a pressure switch malfunctions or a flow switch malfunctions. This can be the case in many situations, however, it is my experience that the number one cause of a spa displaying the error code “FLO” is due to a dirty or worn out filter.
(Some manufacturers attempt to narrow down the FLO error with different displays of the code, i.e., a solid FLO or a flashing FLO (FLO error blinks off and on).
Blinking FLO = Heater has been deactivated, pump is on and Flow / Pressure switch are open. (This means the system detects the spa has called for heat, the PC board has applied power to the pump, but it has not detected water flow. It deactivates the heater to avoid damage to the heater).
Solid FLO = Pump is off, flow or pressure switch is closed. (Meaning, the system should not be detecting water flow because the PC Board has not applied power to the pump, but the flow pressure switch is saying there is water flow. The flow or pressure switch is stuck in the closed position or shorted.)
A dirty or worn out filter can cause several error codes to be displayed. “OH” (over heat) because water is not moving quickly enough through the heater vessel and the high limit detects too hot of water temperature. “FLO” because the filter will not allow enough water through the heater vessel to activate the flow or pressure switch. Filters should be replaced approximately annually or bi-annually if you use two different filters. Filters should be rinsed thoroughly every month, and cleaned properly every 3 months or so.
For more information on error codes for your spa, visit Spa Parts Supply or contact your spa manufacturer for a list of codes that pertain to your spa. When in doubt, call a spa service technician for troubleshooting help and repair.