When you get into high ambient conditions, there are a number of things that can come into play. You need to check clearances on the condenser, air flow through the machine, all of those can affect the chiller in a negative way. One area that can come into play is the high low switch. If the pressures get too high due to lack of air flow, or too hot of air being pulled in through the condenser, the pressure is going to rise in the machine, the switch will trip as a safety to protect that. There is a spring loaded reset on top of the high low pressure switch. Slide that over and let it go in the event that it trips. It could trip due to a bad fan motor, not enough air coming in, a blocked condenser, or hitting it with an extremely high load will cause the glycol temperature to increase dramatically, which will increase the pressures on the system when the refrigerant passes through. You still have a process pump that is running and still sending glycol out, but the compressors can’t run because the high low switch has tripped. That’s when your high and low temp comes in. It’s a safety we install. S1 on it is a 2 stage Ranco located inside your electrical panel. That is the low temp setting that is going to prevent freezing and any low temperature conditions that may occur inside your heat exchanger. It also protects against high temperature situations. If the glycol ever gets too hot because the compressor isn’t running, once it reaches the set point it’s going to shut the pump down to prevent any heat from being introduced to the system.