Prius one Radiator, A/C leak. Patch or replace?

Isn't that the A/C evaporator drain hose? If so, you can expect that to be dripping, especially if the humidity is up there. I would be looking somewhere at the front of the car, where the condenser is, from what your mechanic said. Look for a pipe that goes from the compressor and goes toward the radiator. The A/C condenser is usually in front of, on top of, or at the bottom of the radiator.

Hopefully, someone will be along soon to say where it is on a Gen 1.

 

In Gen 1, the engine radiator and A/C condenser are combined into a single part (with different connections for the engine coolant and A/C refrigerant, of course).

But even though it's a funky combined part, it's really not that expensive, even at dealer list price.

The rest would just be labor for coolant drain and refrigerant capture, replacing the thing, and filling and recharging.

You might be able to find somebody to do that for less than $900.

"Hybrid specialist" A/C shops are in order for Gen 2 and later, because of the high-voltage electric compressor and need for special oil, but a Gen 1 just has a belt-driven compressor like the ones any A/C tech grew up with. Nothing fancy.

 

Refrigerant doesn't leak as fluid so you won't be able to find the leak by looking for that. dolj was right that what you're seeing is just condensate dripping. You won't be able to repair it either, so radiator replacement is about it, but I'm sure you can find a better deal on getting it done.

And it will leak whether you use the AC or not, so you might as well use it.

 

Well, the condenser pressure is likely to be around 80 to 100ish psi or so if you're not using A/C, compared to 225 or so with the A/C in use, so it's likely to leak faster if the A/C is in use.

On the other hand, when the repair is done, that will involve reclaiming all the refrigerant that's still inside and then adding a full charge after the repair, and as far as I know, it's not typical for a shop to credit you for the amount they took out, so it's kind of moot.

I did once manage to get a credit for what came out, when I was repairing an old R-12 system after the stuff was phased out and really expensive, but I had to talk to a couple layers of management, write letters, and watch the tech like a hawk to make sure he wrote down the weight that came out.