Recharging the A/C

[ozymandias]

Our 2004 Prius's A/C has a leak. Rather than pay the 400-500 it would cost to fix it, I decided it would be cheaper just to recharge it once every summer. I tried recharging it for the first time today, but I came accross a problem. Even at 55psi on the gauge, I am still seeing bubbles in the sight glass. I'm a little worried since 55psi is in the "warning" section of the gauge.

The bubbles are quite substantial...they fill up the whole sight glass and it looks "frothy". However, they come and go...sometimes it will be clear and sometimes it will be full of bubbles. So I have no idea what is going on.

Does anyone know if the Prius runs abnormally high pressure in the A/C system?

[galaxee]

did you go to walmart and buy a can of refrigerant? if the answer is yes... bad news.

the prius electric a/c compressor requires the use of nd-11 oil which is not electrically conductive. it is a dielectric oil. nd-8 or normal 134 oils are not dielectric.

so basically it comes down to, cheap out now = pay big time later with a new a/c compressor. if you've already added the oil, which it sounds like you have, the system needs to be flushed out and hopefully no damage has been done to the compressor.

unfortunately this is generally not a diy kind of job. i mean, technically you're supposed to be epa 609 certified to do refrigerant work in the first place.

[ozymandias]

I bought a canister of pure r134a from the auto parts store. It's a can of Dupont, and there is no mention of any sealants or oils. I think you only have to be certified if you are doing work with freon?

[galaxee]

whew- you're in luck! there have been horror stories and we were afraid this was another.

for the record, 609 covers any refrigerant work.

so, where is it leaking and how much oil loss residue is there at the leak? we need to determine how much nd-11 you need to add to the system to get you through.

[ozymandias]

Not really a matter of luck...more of a matter of doing my homework. I knew that I could only use pure r134a when I bought it. It's leaking at the high pressure line at the joint where the sight glass is. There is quite a bit of oil residue at the leak. If I have to pay $90 to get more oil I might as well get it repaired. My real question is, why am I still seeing bubbles at 55psi?

[galaxee]

is the joint a welded joint or a bolted on hose connection? if it's a bolted on hose connection, you can replace the o-ring and they cost under $1.

if you've lost a lot of oil, you don't want to run without it. that compressor needs lubrication.

if there are bubbles, there's not enough refrigerant in there. about 100g of refrigerant is needed *after* the bubbles disappear. the repair manual indicates the quantity should be checked by weight rather than by the sight glass. here are the operating pressures
Gauge reading:
Low pressure side:
0.15 to 0.25 MPa (1.5 to 2.5 kgf/cm2)
High pressure side:
1.37 to 1.57 MPa (14 to 16 kgf/cm2)
they don't give it in psi, of course.

[Patrick Wong]

Originally Posted by ozymandias

Not really a matter of luck...more of a matter of doing my homework. I knew that I could only use pure r134a when I bought it. It's leaking at the high pressure line at the joint where the sight glass is. There is quite a bit of oil residue at the leak. If I have to pay $90 to get more oil I might as well get it repaired. My real question is, why am I still seeing bubbles at 55psi?

The spec is 0.15 - 0.25 MPa (22 - 36 psi) on the low pressure side; and 1.37 - 1.57 MPa (199 - 228 psi) on the high pressure side.

Is your pressure gauge reading 55 psi connected on the low pressure side?

When you see the sight glass clear, this is probably because the compressor turned off or slowed down; I understand that the compressor is variable-speed.

When recharging, do you have the cabin temp set to the lowest possible temp to force the system to work at full capacity?

[ozymandias]

Damn. I am reading 55 psi on the low pressure side. When I first hooked up the hose, it was 45 psi, before I added anything, and the bubbles were constant. I read on here that the 2005 models have an overpressure valve. Is that true for the 2004 as well?

Yes, I have it on max cold with the fan on full blast.

It looks like a welded connection. As far as the oil goes, it says in this post, that the compressor has an oil separator so there shouldn't be a huge loss in oil. Is that true?

I am going to run out and take a couple pictures.

I'm really confused now, it seems that the pressure is too high, but I am still seeing bubbles....what's going on?

BTW, the A/C was noticeably cooler once I added the refrigerant. Maybe the gauge is off? Not likely though I guess.

[ozymandias]

Here is the location of the leak. It looks like a lot of oil, but when I wiped it with my finger, it was actually pretty dry. The green color is from where the previous owner used leak detection dye (another no-no).

[patsparks]

Stop being such a tight arse and go get it fixed properly.
The oil would have mostly blown away in a mist so if you leave it unrepaired you will stuff the compressor, that will be real cheap to fix, not.

That is saying nothing about the refrigerant you are spewing into the air.
This isn't some junk yard get about car, surely it is worth looking after?