It sounds like your trouble may be two-fold there. First, a pressure switch can require calibration upon installation. That is to say, depending on the plumbing in your tub, some adjustment may be required to get the switch to function correctly. A pressure switch should be open circuit (no continuity) when the pump is off, and closed circuit (continuity) when the pump is running. If this isn't the case, the heater will not operate. If you need help calibrating your pressure switch, you can call free hot tub support at Spadepot 800-823-3638. They can walk you through the process. Once you've established the pressure switch is operating correctly, you can look at the second concern.
The second concern is the temp sensor. The first thing to ask is where is the sensor located? If it's in a drywell in the tub, it should be reading the temperature in the tub itself. Often times however, the sensor is located on the heater manifold. While this is fine, the sensor will pick up the temperature in the heater, rather than the temperature in the tub. This can result in different readings until the pump can run for a few minutes and circulate water through the heater. While you could have a sensor that's bad, here's what we'd have you try: Power down the tub and locate where the sensor plugs into the circuit board. Unplug it and inspect the pins and sensor plug for corrosion or any signs of moisture (past or presnent). Plug and unplug the sensor 5-10 times to polish the pins the sensor plugs into. This will establish a good connection. Power up the tub and let it go through it's priming sequence and filtration cycle. Once the pump has run for 3-4 minutes, the topside controller should indicate the correct water temperature. If not, we can look at getting a replacement sensor. Spa Depot's technical department can help with this too.
