Can I replace one section of this AC line or must it be the full assembly?

That's like some kind of aluminum tubing I don't think you could find a person that's capable of welding aluminum to blow some snot in that and seal it up I don't think that would be a win situation and the welder would probably tell you so The block assembly in your picture needs to be taken out of a used car and brought to your car with new o-rings and installed I'm not sure what that pipe cost through Toyota or aftermarket companies like Amiyama. The service port and the block and there may be a pressure switch in there not sure. And if it is it's not removable so you need that whole assembly the easiest way to get it is to like go to an LKQ junkyard and just unscrew it and take it with you or any junkyard that has a second generation Prius or whatever Prius you have they should be plentiful but if you need new I'm sure it's available .

 

Over in Conyers Georgia there are junk yards with miles of Prius I'm not kidding literally they advertised on eBay and all kinds of places so finding this AC line should not be any kind of problem

 

Pretty sure those tubes are press-fit into the union block. You probably don't want to need a press to put it back together.

 

Its an entire assy.

Olathe Toyota here you go:

https://parts.olathetoyota.com/oem-parts/toyota-liquid-line-8870647080?c=bD0yJm49U2VhcmNoIFJlc3VsdHMmYT10b3lvdGEmbz1wcml1cyZ5PTIwMDcmdD1iYXNlJmU9MS01bC1sNC1lbGVjdHJpYy1nYXM%3D

 

For grins you could experiment with JB Weld???? Smear it on and let dry.. Not the correct fix but it should hold the pressure if the metal is cleaned well. But if in a hurry as its getting hot....buy a whole new assembly.

 

JB Weld seems like a waste of R134 as it will probably leak under that pressurized system. It can get really costly if you try to shade tree a car ac system.

Also if it leaks your putting your compressor at risk of running under low pressure which can damage the compressor. That's $550 for the OEM compressor + installation and since its an electronic 3 phase compressor omg that's super dangerous and super expensive to install lol.....At least that's what they'll tell you at a shop to drill you.

Pre covid having my under dash condenser replaced the ac shop told me your lucky you brought it in before you damaged the compressor because we charge $900 for a Toyota oem compressor + labor. You know it's electric right? lol..

https://parts.olathetoyota.com/oem-parts/toyota-compressor-8837047010?c=bD0xJm49U2VhcmNoIFJlc3VsdHMmYT10b3lvdGEmbz1wcml1cyZ5PTIwMDcmdD1iYXNlJmU9MS01bC1sNC1lbGVjdHJpYy1nYXM%3D

 

It's too quick to run to a spare car somewhere and just take the part off complete none of it's pressed together it's aluminum tubing and a block and whatever other pieces It doesn't come apart.

 

When in a bind, surprisingly, JB weld works very well, but it needs a backing plate for this type repair. I know it sounds unusual, but this works:

The surface of the aluminum needs to be scuffed with sandpaper.
Fabricate a "spring type" backing plate that is long enough to extend ~3/4" from the damage in each direction. Looking at the plate from one end, it should look like a "C" with the inner edges of the C rolled a bit outward to allow the backing plate to be pushed onto the tubing. The diameter of the C should be a close fit to the diameter of the tubing so it pops on tightly. Google "spring steel cable clip" to help visualize it.

When you have the surface prepped, epoxy a (very) small piece of sheet metal over the hole carefully so epoxy doesn't go squishing into the hole. After that is cured, smear epoxy on the tubing and on the inner surface of the "clip". Press the clip over the damaged area of the tubing and seat it firmly. See the drawing below. The spring action of the clip will keep it seated tightly as the poxy cures. I have a Trane R410A 3.5ton heat pump that developed a pinhole big enough to insert a pen point in the aluminum portion of it's lower coil where it transitions from aluminum to copper. After a few unsuccessful "professional" weld repair attempts and prior to having significant damage done, I was told I needed to just replace the unit. I had everyone GTF away from it. I did this repair and the unit has been functioning flawlessly for 3 years. I'm pretty sure R410a is significantly higher pressure than R134a