2003 freightliner Columbia AC issues

I am only getting about 58- 60 degrees from the vents . I have vacuumed the system twice and filled . I then thought about the heater / cold valve by the fire wall . I tried blocking off the valve to stop hot water / heat from getting into the cabin ..I think there is only one line going into this valve and the other side of the valve goes straight to a hose that's connected to the dash . The compressor cycles and the fan comes on . Is there an AC filter for this Columbia ? My century has an AC filter by the firewall but I see none for this Columbia . How can I bring this temp down from 58 degrees ? Btw , I have all the coolant faucets closed to prevent heat

 

I am new to this ? Expansion valve ? Is that the one behind the trucks air filter box ? I have a dryer (black) , I don't think I have an expansion valve . when I vacuumed , I didn't check for leaks because my mechanic had just used his vacuum machine a week ago , and I was getting the same 58 degrees .Even with the right level of refrigerant , I am getting the same 58 degrees .

 

This was why I went behind my mechanic and changed the dryer and its O ring , and I am still getting the same temp .Should recirc be closed or open ?

 

Yep , the expansion valve and its O ring is what I changed . Does anyone know how to read pressure by using the AC manifold ? I mean this truck takes 3. 75 cans or 48 pounds of Freon , but if I want to top it , how can I read the gauges , by knowing how many pounds is already in there ?

 

Oh! I see. I saw them . someone said they rarely go out, but you may be right

 

Wow! Thanks a lot 1