There are two different sensors that can indicate “high temperature”. One is a thermistor, and the other is a temperature switch, both located on top of the stainless steal vessel.
The last thing to note is that they both reference ground. If they lose their reference to ground, the high temp indicator will light up. To check that your ground connection is secure, from inside the controller, using a volton meter, first disconnect power. Check the thermistor (yellow wire) to ground. It should read, at room temperature, approximately 48 ohms. The temperature switch (orange wire) to ground should be straight continuity.
It’s a timing circuit that shuts down the PREVAC when something is preventing PREVAC from bringing the pressure to the set-point.
This is caused by water flow through the chiller (condenser OR evaporator). Address the reason for the water flow.
The pressure transducer is not connected.
At full power, check the inlet temperature and the outlet temperature. A temperature rise of 5 F -10 F through the vessel means you have good water flow. The lower the temperature rise, the better the water flow.
If you have a temperature rise of around 15 degrees, you have a problem with water flow. This means one of two things:
Make sure power is off to the PREVAC. Right from the terminal, with an ohm meter, check from H1 to H2, H1 to H3, and from H2 to H3. For the 480v system, all the readings should be the same, around 23 ohms. To check an individual heater, the reading should be 69 ohms.
For the 240v system, from line to line 9.8 ohms. The individual, 28.9 ohms.