My 2013 Prius (150,500 miles) is having issues with poor A/C performance so after checking for bubbles in the sight glass, I moved on to using manifold gauges. The 2010 Service Manual gives information on how to INSPECT REFRIGERANT PRESSURE WITH MANIFOLD GAUGE SET and the first test condition is "Temperature at the air inlet with the switch set at RECIRC is 30 to 35°C (86 to 95°F)." This may sound like a stupid question (it wouldn't be my first) but what air inlet is it referring to and how would it be controlled to be between 86 and 95F? The other thing that I thought strange is that the third test condtion is "The temperature control dial position is at "COOL"." I don't have a temperature control DIAL and the digital display does not show COOL but I used the LO setting. Would this perhaps indicate that these instructions were copied from an earlier Toyota model, maybe not even a Prius? Therre's no mention of whether the Power button should be set so that Ready is displayed so I just had the A/C running on battery. Unfortunately, the only pressure tables shown are for normal operation but it would have been helpful if they had also included pressure ranges for the various fault situations, instead of just gauge images. Mine both showed around 70psi so, it looks like my refrigerant level is low. Initial tests with a halogen leak detector show that both schrader valves are leaking slightly. At least, when I remove the caps, the detector goes nuts then stops beeping. However, if I try it with the compressor running and the caps off, it doesn't indicate but after running with the caps on for 10 minutes or so, it beeps again when they are removed. My theory is that they are not leaking very much but enough to accumulate under the caps and trigger the detector when opened. I checked for DTC's using the Auto and Recirc buttons and it showed 00. I also hooked up Techstream and again it showed no codes. The compressor speeds were all just a couple of revs short of target, at the various settings so I'm hoping that there are no other problems. I plan on taking it to a local shop to have the refrigerant removed and hopefully, they can do that without removing any of the ND-11. I'll replace the valve cores with a smidgen of Nylog Blue to ensure a good seal, evacuate and recharge by weight. One good thing is that it has started to cool down here in Florida but there are still some days when A/C can make a difference. I plan to replace the car sometime in early 2026 so maybe this will keep us comfortable until then.
