[VStar650CL]

Also check for a bad refrigerant pressure sensor.

Might just not have enough refrigerant. That's what the sensor is there for. The ECM won't let the compressor turn on if pressure is too low.

 

[VStar650CL]

You should probably check the voltage on the sensor before you assume it's low on refrigerant, you don't want to overcharge in case it's a bum sensor. They all have 3 wires, one will be 5V, one will be ground, and one (usually the middle) will be signal. Back-probe it with a safety pun. Even if the system is empty, with the key on you should see a small voltage on the signal line. If the system is just low, you'll see something below 1V. Static pressure around 1V is normal, that would mean it's charged and the sensor works, so something else is wrong. If it reads 0V it's a bad sensor, they almost always fail flatlined at zero.

 

[VStar650CL]

That one is a sensor, I have no idea why CARiD is calling it a switch. It fits just about everything Nissan from '00 to '10, so I'd say it's a good bet it's right for your '06. However, I have no way to check, we have zero documentation for Exxies here in the 'States.

 

[VStar650CL]

Even a leak-free A/C system will gradually lose refrigerant over time from "osmosis" through the seals and hoses, just like tires will eventually go flat from air molecules migrating right through the rubber. Healthy systems usually need a top-off every 3~5 years. So yes, I'd say there's a very good chance you're simply out of refrigerant.