Right.

So on the above graph it is along the blue line. A phase change occurs. Either liq -> gas or vice-versa. It's the phenom where the working fluid either absorbs or releases the greatest amount heat.

I'm still working on understanding the terms you use, relating them to words/concepts a physicist/physical chemist would use.

I'm assuming high T gas enters the heat exchanger before the radiator. I think it's called the condenser. Here the gas turns into liq, the point at which that occurs being the saturation point. That is the temp at which it turns into a liq depending on the gas P in the condenser.

Continuing on at some point the cooled liq expands to cool the car. I'm thinking this may be metered and takes place within an expansion chamber. It's possible metering takes place before entering the compressor. I don't know I'm getting my handle on the physics. I need to learn that first and then I 'll learn your terms.

Anyway the process in the expansion chamber, where I'm thinking liq -> gas, the T at which that occurs depends on the P at that point and is also a saturation point. Which would be found on the blue line on the phase diagram.

I'm speculating in my comments. Please correct where I'm wrong & since this is a sticky alter, delete as best. If this is the wrong thread to be asking these questions I'll do it in a different area.
.