We have a Sweetwater Cayman Spa that is not heating up after we drained, cleaned and refilled it. I’m looking for any additional troubleshooting advice beyond what I’ve already done. Details below.

The spa was built in October 2003 and has been serviced twice since we bought it new. Once, the temperature sensor was replaced (October 2004) and the other time it was only an airlock problem that the technician quickly resolved.

This spa has a somewhat unique setup compared to most that I’ve seen on the Internet.
- The control pack is a Sweetwater.
- The heater is made by Laing, Model SHE-5500-NHC, part no. 6698. It’s a large U-shaped pipe with a black plastic box surrounding where its mounted to the electrical housing.
- The main board is a 6600-088 Sundance Circuit Board
- The Hi-Limit sensor is simply a thermistor that’s strapped to the heater pipe with a hose clamp.
- You can go to this web page to see photos of the circuit board, hi-limit sensor and water temperature sensor: http://www.spacare.com/6600-288sundancecircuitboard.aspx
- The flow switch is mounted in its own see-through t-adapter. The switch has a little brass spring/paddle that’s forced against a “probe” when the water flows. There’s no adjustable components on the flow switch. You can see a picture of the flow switch here: http://www.spaandpoolsource.com/2560-040sundancespasflowswitchsweetwater2003-20042005-2006palermobahiaandcayman.aspx

The symptoms are:
- no heat
- Often, the control panel display gets all erratic and randomly flashes single digits or characters.
- control panel displays water temp as 57 degrees. A hand held digital thermometer shows water temp as 60 degrees – pretty close.
- On startup, control panel does its normal thing
o Displays EPROM rev number 3.5.5
o Displays 8.8.8 and heater indicator comes on momentarily.
o Displays temperature
- Occasionally, but not always, the control panel displays ICE. This is expected since we filled the spa with cold water.
- Circulating pump kicks in occasionally for brief durations
- Main pump kicks in occasionally for brief durations
- Heater never kicks in. No power present on heater element leads.
- Air temperature here in Northern NJ is in the low 40’s this afternoon.

Here’s what I’ve done so far:
- Put my ohmmeter on the flow switch leads. Reads high ohms when no flow, effectively 0 ohms when water is flowing.
- Checked nominal resistance of water temperature sensor. At 57 degrees water temp, the temperature sensor reads around 50 ohms. Using a garden hose, I ran hot water over the sensor and the control panel temporarily read 100 degrees.
- Checked nominal resistance of Hi-Limit sensor. It is 48 ohms. If I warm the Hi-limit sensor with my hand and breath, the reading drops to around 35 ohms.
- Checked resistance of heater element – 11.3 ohms, that’s within 10% of calculated spec of 10.5 ohms.
- Confirmed presence of 240V on heater relay input. Then put voltmeter on heater element terminal while the spa is operating. No power is ever sent to the heating element. Note: the heater control circuit includes two “ganged” relays. I assume this is for safety reasons, i.e. this design eliminates a single-point of failure if one relay should stick closed.
- I confirmed that the circulating pump operates and that I can see/feel water being pumped into the spa.
- I removed the flow switch lead from the circuit board and temporarily jumpered (shorted) the flow switch pins on the circuit board to simulate a closed switch. This did not change the behavior of the spa.

Do any of these results indicate the likely source of the problem? What other troubleshooting can I do?

Thanks in advance for any additional troubleshooting advice you can offer.

I also need to mention that I confirmed that the transformer is in working order. I disconnected it from the circuit board. Powered the primary with line volage and got the expected output from the secondary.

Steve

Hi, I am having the same problem, Drained tub to move it, now having exactly the same problem as your tub. any answers to the problem yet?

Unfortunately, the problem was a bad circuit board. I ended up hiring a technician to troubleshoot the spa and all the sensors and other electronics tested fine. He solved the problem in less than an hour.

One clue to the problem was that the display kept showing all dashed lines even after the start up cycle. He reminded me that this means the spa's watchdog software was kicking in and preventing the heater from starting.

I ended up buying a used board from him for $250. Otherwise, his charge would have been $450 for a new replacement board.

However, I found this site selling the new board for $295:

http://www.spacare.com/6600-288sundancecircuitboard.aspx

The total charge for his visit came to $400 ($90/hour labor + $60 travel fee + $250 parts), but he was an excellent and personable tech.

The handiest tool in his kit was an ammeter - the type that has one end that loops around the wire to see how much current is flowing. With my old board installed, it was easy to see that no current was being sent to the heating element. The replacement board worked like a champ and the spa's been fine for over 2 weeks now. Hopefully, the used board will give us several years of service.

All the best,

Steve

Oh, one more thing. Before you go crazy troubleshooting the electrical/electronics of your spa, make sure that you don't have an air pocket preventing the normal flow of water in your circulating pump. The user guide has instructions for clearing an air lock.

All the best,

Steve

Well thanks for w/b, I am also leaning in the board direction. Continuity tested the flow switch jumped the circ. pump & hi-lo on the main pump they run, the relay clicks in and tries to start but no!!!! luck, its not air locked pumps run get good flow so its got to be the board ?