1985 Oldsmobile Cutlass 442 I'm replacing all A/C lines because of new compressor my question is the small line that goes to the evaporator does not have a place for an o ring seal
there is 1 at the other end to the condenser

 

I'd look again. I bet you just overlooked it or don't recall seeing it. If it's a GM part, it's got a place for the seal.

 

The plastic orifice tube is clamped between the evaporator inlet and that metal line. The o-ring is built into the orifice tube. The long end of the orifice tube goes into the evaporator inlet, the short end into the small diameter metal hard line.

 

But there's also supposed to be a 1/2" O-ring for that condenser to orifice connection for the tubing as well. The orifice o-ring is an internal seal just to seal off the high pressure side from the low pressure side of the orifice, ensuring all the refrigerant goes through the strainer screen through the orifice.

#8 in the drawing below is the O-ring to look for if I'm understanding the question correctly. Strangely, this pic doesn't even show the orifice tube here, but it's shown with the A/C and heater module assembly blow out diagram. 3033879 is the GM part number (or equivalent) for the correct orifice with o-ring, which was used for a gajillion cars of that era. In fact, the part number is still good at GM dealers, listing for $11.51 retail.



That O-ring should be hanging off the end of the high pressure tube sitting on its landing as you can see in the pic below.