You're boned
In the liquid (low pressure) line at the condenser connection.
The orifice tube is built inside the liquid line and can not be serviced separately.
If you mean the orifice tube, it is in the low pressure line. If there is a hex nut in the line, you can separate the two parts and remove the orifice tube. If there is no nut, just a crimp, the line must be cut and a repair kit installed to contain the new orifice tube.
40 psi
You have a fixed orifice tube is located in the liquid line, between the condenser and the evaporator coil. If the fixed orifice tube is faulty or plugged, the liquid line assembly must be replaced.........
Buick Century is the model name used by the Buick division of General Motors for a line of full-size performance vehicles from 1936 to 1942 and 1954 to 1958, and from 1973 to 2005 for a mid-size car.
You could, but you will have to buy a new line to get a new orifice tube.
u dont
Look under vehicle along frame rail - follow fuel line from tank
How do the timinh marks line up for buick ventury 1990 with a 6cyl 3300 engine
Some are in the inlet to the evaporator and some could be in the condenser line.
I'd suspect a loose, damaged or unhooked vacuum hose/line around the upper/lower intake. Or a faulty throttle position sensor.