A C compressor causing P0AA6 code

*starts stopwatch*

 

This thread?

 

Not that I've noticed...

 

Are there any trouble codes from the HVAC system now? Those are mostly B14xy codes.

If you haven't got a scan tool that shows them, you can retrieve them without one; look for "Codes from the heat/air conditioning system" toward the end of this page:

Blink (a/k/a Flash) Codes – How to. | PriusChat

I don't know that I'd take a chance with a homebrew flushing solution, whether acetone, isopropanol, or what not.

There are flush regimens that have been used on hybrids when the wrong oil got in (you can search threads here for HECAT), but I don't know if that's anything you could do to a manifold set, for less money than just buying another manifold set to keep dedicated for hybrids.

 

In the gen 3, that is a pressure transducer, not a pressure switch. So it isn't just ok/not-ok, you can actually read the high-side pressure using a scan tool.

With the compressor not running, the equalized pressure can be looked up on any R134a "saturation pressure / temperature" chart; given a pressure gauge and the chart, you've got yourself a thermometer. (The temperature that matters is the temperature of the refrigerant and piping in the car, not necessarily the temperature your outdoor thermometer shows.)

The trouble with the equalized pressure is it doesn't tell you a lot. You will see the same saturation pressure from less than a full charge clear up to more than a full charge, as long as there is enough in the system for any of it to be liquid.

If you add some more refrigerant, more of it condenses to liquid and you still see the saturation pressure. If you let some out, more of the liquid evaporates, and you see the saturation pressure.

You'll see a lower pressure only if you are very low on refrigerant—low enough that all is vapor and no liquid remains. So if you see a pressure much lower than the saturation pressure, that does tell you a lot is gone. But once enough has been added to have some liquid again, the pressure will stop telling you much.

I'm not familiar with Creader-Toyota. Have you checked the HVAC blink codes, just in case that reader doesn't speak HVAC?

 

A gen 3 will report (most) HVAC trouble codes both as DTCs to a scan tool and as two-digit numbers on the HVAC display. (How to trigger the code display is on the blink-code wiki page, but only gen 1 actually blinked the codes. As that page says for gen 3, "Look for two-digit codes shown at the left end of the HVAC display. The two-digit code xy usually means the same as a B14xy code shown on a scan tool.")

There's a displayed two-digit xy code to go with every B14xy DTC except for two uncommon gen 3 codes B14A1 and B14A2 (because the display can only show digits 0–9). Also, the comunication U codes from the HVAC do not have two-digit display versions.

There's no code that means specifically "low on freon". As usual, an ECU can only tell you things it has some way to know, so the closest you might get is the B1423 code (about an out-of-expected-range pressure sensor reading) or one like B1476 (about the compressor needing an unexpected amount of power). Whether the cause of such a code turns out to be the amount of refrigerant is something the human has to work out.