You slip on a bathing suit and head out to the hot tub, jump in and realize it’s lukewarm. Glancing at the control panel the “Power” and “Ready” lights flash and the panel reads “=========” – what’s up? Most likely it’s not an expensive faulty heater but rather a part that costs less than $60.
Basically, your hot tub has shut down because there is not enough water flowing through the heater due to either an air bubble or a faulty pressure switch.
Did you recently change the filter or the Frog chlorine cartridges? Did you recently fill the tub? Is the filter clogged?
You can try to force water through the system with a hose. Put the hose down inside the filter cavity.
You can also try removing the filter and opening the Frog chlorine hatch.
I have a Hot Springs Hot Spot SX hot tub but the manufacturers often use the same parts for control panels, circuit boards, sensors and heaters. For example, most of the components of my hot tub are actually made by Balboa. So the error readouts on one hot tub are typically the same on others. Even from year to year the control panels and software behind them don’t really change that much. So if you don’t have my exact same hot tub model, these troubleshooting ideas might work for your situation and can save you an expensive service call.
Dirty Filters are the number one reason for a Hot Tub or Spa to shut down
A hot tub will stop heating if there is air in the line or if the pumps can’t move enough water through the heaters. Try removing the filters and then activate the pumps. If the hot tub works without the filters, then you have dirty or clogged filters.
Put in a new filter and soak the older one in some filter-cleaning solution. Clean your filters every month. To remove air in your lines, remove the filter and stick a garden hose down in the bottom where the circulation pump sucks in water.
If all else fails…
If this all fails, you might have a faulty pressure switch. The pressure switch is a $60 part and is rather easy to replace so you can just order the part and save yourself a service call charge.
This is the part you need for most Hot Springs and Hot Spot spas.
Watkins Pressure Switch 73995 Fits Various Caldera & Hotspring/HotSpot Spas
Testing a hot tub pressure switch – https://www.youtube.com/watch?v=-KsUGcQMGxQ
Replacing a hot tub pressure switch
Problem: Spa does not heat, jets and lights operate. Display displays “==========” POWER and READY flashes.
Probable Cause: pressure switch is closed and should be opeN
How I fixed my Hot Springs Hot Spot SX
So I was getting the dreaded “==========” message with the POWER and READY flashes on the LCD screen and the hot tub was not heating up.
Winter was setting in and I was leaving town for Christmas in a couple of days so I kind of panicked. I quickly ordered a new pressure sensor from Amazon – https://amzn.to/3Wd3HDs but it wouldn’t arrive in time before my flight to Texas. I was getting worried that the hot tub would freeze up while I was gone.
So I took a look underneath and discovered that the pressure sensor was disconnected! The guy who installed the hot tub must have knocked the connections loose and the vibrations from the hot tub must have wiggled them off.
I crimped the connectors tighter and stuck them back on and the hot tub fired up. I’ll keep the replacement pressure sensor for a future repair as they tend to fail after a few years. Since they come with a wiring harness, I’ll solder the old one onto the sensor to make sure it doesn’t pop off in the future.
High Limit Switch Failure
If the problem is not the pressure switch, it might be the high-limit switch that is keeping your hot tub from heating.
On the Hot Springs Hot Spot SX and other models, the high-limit switch is a little silver torpedo-looking thing that is attached to the outside of the heater with silver tape.
If just the POWER is flashing and the READY is not lit and you have those ten “=====” lines, it might be the high-limit switch.
The high-limit switch prevents the hot tub from reaching dangerously high temperatures.
Each spa is equipped with a thermistor that is used as a temperature sensor. The thermistor is a semiconductor that changes resistance with temperature changes (as the temperature goes up, the resistance goes down). A comparator circuit then compares the voltage to the set point voltage. If the voltage differs the heating circuit is sent a signal to energize the heater system or terminate the system if the voltage is equal to the set point.
The set point is the spa’s default temperature (102°F) unless reset at the control panel’s up or down temperature set buttons. The high limit is designed to disable the heating system and controls but keep the circulation pump running protecting against freeze damage in winter conditions.
NOTE: BYPASSING A THERMISTOR OR SHORTING THE TERMINALS WILL CAUSE THE SPA HEATER TO SHUT DOWN. NEVER ATTEMPT TO BYPASS OR ELIMINATE A THERMISTOR FROM THE CIRCUIT. TO CHECK THE THERMISTOR COMPARE THE RESISTANCE TO THE THERMISTOR CHART. THE WATER TEMPERATURE AND THERMISTOR SHOULD BE THE SAME.
Cold Weather Start-ups.
In below-freezing climates, technicians and delivery personnel occasionally run into symptoms of electronic high-limit tripping when trying to start up a new spa (or a spa that has been stored empty). In the high limit tripped condition, only the circulation pump will operate (the heater, lamp, and jet pump will not operate).
High-limit tripping at start-up is most common in spas that have been stored outside or in unheated areas. This is because the thermistors installed in empty spas are sensitive to very cold weather (in filled spas the warm water keeps the thermistor in its normal operating range). If the temperature of the high-limit thermistor is near or below 45 degrees F, its resistance increases significantly.
The very high resistance of the cold thermistor is outside of the normal operating range, so the high-limit circuit shuts down the spa. The second set of thermistors kept in a warm environment Can be switched out prior to powering up the spa. This will keep the system running until the original thermistor warms up.
HIGH-LIMIT SENSOR Removal:
1. Disconnect power to the spa.
2. Remove the front access panel.
3. Open the control box lid.
4. Unplug the high limit sensor from the control box high limit terminal and remove it from the control box.
5. Trim any zip ties that hold the cords in place.
6. Remove the hi-limit sensor from the clip on the heater.
Installation:
Reverse the removal procedure to install the control sensor in the equipment compartment taking special care to apply insulation to the backside of the control sensor.
Failure to replace the insulation around the high limit and heater will result in the possibility of the spa shutting down during the winter months.
Note: After installation, switch the jet pump to high speed and check spa functions.
73992 High Limit Sensor is for the following models:
| Make | Model | Date Range |
| Hot Spot | Relay | 2010-Current |
| Hot Spot | Relay | 2013-Current |
| Hot Spot | Rhythm | 2010-Current |
| Hot Spot | Tempo | 2010-Current |
| Hot Spot | SX | 2011-Current |
| Hot Spot | TX | 2011-Current |
| Hot Spot | Mallorca | 2006-2009 |
| Hot Spot | Sorrento | 2006-2009 |
| Hot Spot | La Palma | 2008-2009 |
| Hot Spot | Tobago | 2006-2009 |
| Hot Spot | Trinidad | 2006-2009 |
| Solana | SX | 2006-2010 |
| Solana | TX | 2006-2010 |
| Solana | RX | 2006-2009 |
| Caldera | Palatino | 2010-Current |
| Caldera | Marino | 2010-Current |
| Caldera | Vanto | 2011-Current |
| Caldera | Aventine | 2006-2015 |
| Caldera | Cumberland | 2006-2009 |
| Caldera | Olympia | 2006-2009 |
| Caldera | Tarino | 2013-Current |
| Caldera | C 30 | 2006-2009 |
| Caldera | San Gabriel | 2008-2009 |
| Caldera | Oasis | 2006-2009 |
| Caldera | C 45 | 2006-2009 |