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Subaru ac low side WAY overpressured

I have a 2000 Subaru Outback with 240k miles on it. Tha AC doesn’t work. It was taken to the mechanic recently (about a month ago) and he said it just needed a little coolant - that it had a very slow leak. So we had the coolant added. The AC worked for a fe weeks, but it took longer and longer to cool down, until it was taking almost an hour to get cool.



I figured I didn’t have anything to lose so I went to the auto parts store and bought a bottle of AC stop leak and a gauge. I figured I should check the low side press before I started, and to my surprise found the low side ores sure to be around 100 psi (I can’t read the actual figure because it’s over the gauge max). So now I understand why the AC doesn’t cool - the pressure drop is what causes the cooling effect - but I don’t understand what is causing the overpressure in e first place. Can anyone give me some ideas?

I am not an AC tech. But I can tell you that you just need to bite the bullet and take the car to one. First, you really just need to have the leak fixed and without a lot of expensive equipment, training, and other tools you won’t do it. A/C systems are just plain old complex.

The thing about the low side pressure is that the “normal” range on those store bought gauges is assuming that the compressor is running. If your refrigerant level is too low the compressor won’t run and the low side pressure will remain quite high. However, you are saying over 100psi. I’m not a tech but I’m pretty sure that is too high.

Short story: you need to bite the bullet and just have a good AC shop check it over and fix it.

The compressor needs to be engaged to pull the low-side pressure down. Unless the compressor is running, system pressure will be equal on both sides, around 110 psi…The system must be operating in order to recharge it…

I thought it was more like 90psi - but I am out on a limb here. Either way that compressor isn’t running, and you can’t get a read on it that way.