Updated for 2018.
1. Initial investigation
Many techs start by lifting the cover, which tells all about the water’s chemical makeup — discoloration in the cover will show the spa’s entire history. For example, water with a low pH level burns the cover, so the center would be white. That should signal to the tech to go directly to the heater to look for chemical damage at the heating point.
Also, the filter should be checked early on. A clogged filter can cause a number of failures. If you suspect that a pressure switch needs replacing, for instance, it really could be the filter’s fault. If the filter’s dirty, there may not be enough water pressure throughout the system, causing the switch to be triggered. The location of the filter cartridge is helpful to note. A dirty filter cartridge on the suction side of the pump will drop the pressure at the heater, while one located pressure side will often increase it. Also, if you have a sealed canister on a suction-side filter, you can have issues with a bad O-ring or cracked lid that can cause a pressure switch not to engage.
2. Pinpoint the problem accurately
Begin by checking the main component itself. Use a voltmeter or multimeter to determine whether the pump, heater, blower or another piece of equipment is receiving power. If it is, you’ve found your problem. If not, then a switch or relay likely isn’t transferring the current. Be cautious of “ghost voltage” on modern circuit boards. On many of the circuit boards in use today, power output to components can read voltage when the circuits are not turned on. This is particularly a problem when there is nothing plugged into a circuit. If you suspect this is the problem, it is often a good idea to plug it into a circuit you know is functioning to see if it is actually faulty before ordering a replacement.
Depending on the symptom, you may want to consult an electrical schematic for the spa, if one is available. Then you can see which series of switches and relays are involved. Next, work back from the main component, checking each relay or switch in the control box.
Certain areas are tougher to inspect than others. When dealing with a spa that’s more than a few years old, it may be difficult to tell when a circuit board is causing the problem or whether it’s the topside control.
The diagnostic mechanism will provide a code, but that could apply to either component. For such tricky diagnoses, plug in separate units to see if they work. Many techs bring along additional topsides for testing purposes. They disconnect the client’s topside, plug in theirs and, if they get the same reaction, then it’s the board that’s bad. If it works with the new topside, it’s the topside that’s bad.
Some brands of spa control will run without the topside control plugged in. If you have something odd going on, try restarting the circuit board with the spaside unplugged and see if things improve. Some modern systems can take a while to start up, so without a screen display you will want to wait about five- to six minutes to see if it starts running on its own.
In some instances, the problem may not be a faulty part at all. If the system doesn’t heat, it could be a restricted flow. Check the plumbing for leaves or other debris that may have caused a clog. If the unit contains a pressure switch, a little sand or dirt may also plug it up, preventing the heater from sensing the system pressure.
If the circuit board was recently replaced, make sure to review the positions of dip switches and control jumpers. It’s good practice to set them in the same setting as the original board.
3. Close it out
After the repair, conduct a full diagnostic assessment of the spa. Among other items, check chemical balance, the heater terminal at the bulkhead fittings, the air-check valves, jet selectors and buttons. Look for burned wires. Evaluate every screw in the pack to make sure they’re all tight. Make sure all the wire connections are proper.
Finally, remember to test the ground fault protection system during each visit. If you notice something that could cause another failure, notify the customer.