Hopefully, an expert on this forum having first-hand knowledge of converting the same or similar vehicle you have will see this thread and offer advice. Earlier, you alluded to an acquaintance who helped you re-charge the system with the original refrigerant. Unfortunately, that re-charge didn't las...

I have no direct experience converting a vehicle just like yours. But if you choose to go the conversion route, the system will have to be thoroughly flushed to remove all traces of the old mineral oil, replacing that with PAG or ester oil. Components to flush include the evaporator, hard lines, and...

I'd have a professional shop find the leaks, repair them, and keep it R-12. The system was originally designed for R-12, and cooling surely won't improve by converting it to R-134a, especially since you mentioned that it didn't cool sufficiently to begin with. In fact, you'll probably lose a bit of ...

Here's what my references say: 21.0 ounces of R-134a and 4.0 ounces of PAG-46.

I haven't heard about a recurring problem as you describe with the 2007 Yaris A/C system. But to answer your question, yes, there are several manufacturers of in-line filters designed to trap debris before and after the compressor. Santech is one. Check with Tim on this forum, who I'm sure can provi...

You mentioned that you checked the connector at the compressor, but do you see voltage there with the system turned on?

I would take the advice of bohica2xo, then, and adjust the low-pressure switch upwards in small steps until you see the compressor begin to cycle. Other than that, the system seems to be performing pretty well.

Your Audi calls for 23.0 ounces of R-134a and 8.5 ounces of PAG-46. If it still has the stock A/C system, the engine swap and custom hoses shouldn't make any measurable difference. I have a few more questions. You mentioned that you evacuated the system, but for how long? A short time (like 30 minut...

How did you charge it?

Assuming the charge is correct now, a high side of only 100 PSI suggests that the compressor isn't up to snuff unless it's a variable-displacement type compressor that's partially or fully de-stroked at the time of testing.

I don't think you mentioned your vehicle's make, model, and engine size. Need those for an accurate diagnosis. In addition, testing with a manifold gauge set should be done with the compressor engaged, max A/C selected, blower on high, windows down, engine at about 1,800 RPM, and vent temp noted. Is...