Expansion valve, if I'm not wrong and dumb, it is the one in evaporator unit inside the cabin? ... I had noticed a whistling when i turn on the AC, that comes from the evaporator unit.
... Thermostat valve yes ... As far i as know but i can double check on that. I'm also a bit suspicious about the circulation.
Unfortunately, the mechanic couldn't understand all my blabbing today and said, all is okay with your car, don't worry. But I'm, since I'm planning on taking this little hatchback to Gilgit, Hunza, Sost side in July, InshaAllah