AC compressor question

[1-3-2-4]

ahh I see something I did wrong.. ugh stupid gauges...I'm not used to screwing something down to open but that's how these quick connects are...

[SubyFusion]

Yes the low should show up high on the gauges only because of the pressure in the can. have you finished charging it yet? how many cans do you have in??

[1-3-2-4]

I'm done charging

[SubyFusion]

how is it working? is it cold yet

[1-3-2-4]

nice and cold

[SubyFusion]

Awesome I am glad to hear everything is working great

[Legacy777]

Glad you got it figured out!

[Legacy777]

Josh I would like to know the steps you took to charge your system

Here's the write-up I did a couple years back.

http://bbs.legacycentral.org/viewtopic.php?f=11&t=1083


The things that I have changed since then was that I have used PAG 100 oil rather than esther oil because the PAG oil lubricates better. I kept killing compressors on esther oil.

I've also since bought a vacuum pump and will pull a deep vacuum for about 45 - 60 min.

Regarding the pressures on the high side, I need to double check the HVAC book I have. However, they will vary depending on ambient temperature. So to say they are always going to be at a certain point may not be true.

The other thing may be that I am only running about 75% of the original refrigerent charge in my system since it was designed for R12. I believe R12 runs at lower pressures. An original R134a system may run at higher pressures. I just don't recall ever seeing pressures as high as 400 psi, but I could be mistaking.

I final broke down and bought a new compressor when I did my engine swap a couple years back. I've done several compressors on the Legacy, recharged the system several times, and recharged the Impreza. AC work is one of those things it's kind of an art form. There's more than one way to do something, and depending on certain conditions, there's more than one right answer.

Also, a note I was told about the sight glass is that on R134a systems, the sight glass is useless. That's why you don't see them any more. Looking for bubbles on R134a charged AC systems is probably not going to tell you much. With my Legacy, it just looks like a foam/frothy mess.

When I finally get my engine rebuilt and back in the car, I will need to recharge the system. It's been open to the atmosphere for quite a while, I'm probably going to pull everything and flush it so I know it's clean before recharging. You've got to have AC in Houston. It's absolutely miserable without it!

[SubyFusion]

During my research I read that PAG oil does not my with the mineral oil from the R12 but the ester oil does, thats why I used it, but i think I am going to regret it because my pump is making noise already stupid ester oil! o well at least I know what to use now.

What do you use to flush the system out?. Ya the a/c guy told be to use the sight glass he must be old school I guess, it was white and foamy but only after the bubble disappeared and the freon took its place, but thats why I have gauges. my system said it take 32 ounces, should I charge by ounces or by pressure?

[1-3-2-4]

should charge by ounces... pressure can be effecting by temp changes.

[SubyFusion]

Thanks Thats how I did it. Do you really have to change the receiver/dryer? I never did and it work fine!.

[1-3-2-4]

Thanks Thats how I did it. Do you really have to change the receiver/dryer? I never did and it work fine!.

I don't think I showed mine here but I think mine is factory....

[SubyFusion]

So should I replace it or not? what happens if i don't??

[1-3-2-4]

Serious? It can no longer dry the A/C system thats why they call it a filter/dryer it's job is to filter out and dry any moisture out of the system so the lines wont corrode.. R-134a and moisture make a very bad combo.

And besides mine was only $20 if you think that's too high then I can't help you...

[SubyFusion]

I know what it does!!! I am not stupid. I didn't replace mine and it works great so I don't see any reason to bother.

[1-3-2-4]

Pissssssss.... that's the sound of my high pressure line leaking going to be fun trying to find the part number for that line that runs from the dryer to the evap core let's hope it's not made from Subaru gold...

Damn.. from what it looks like those damn little pipes on subaru parts.com is $94 without shipping.. why are two little parts cost so much?

[93forestpearl]

Are you sure your temp sensor in the evaporator is good? They can fail on these cars.


Yesterday I ran a switch to manually control the compressor, filled the system, and found out my compressor is junk.

[Legacy777]

During my research I read that PAG oil does not my with the mineral oil from the R12 but the ester oil does, thats why I used it, but i think I am going to regret it because my pump is making noise already stupid ester oil! o well at least I know what to use now.

What do you use to flush the system out?. Ya the a/c guy told be to use the sight glass he must be old school I guess, it was white and foamy but only after the bubble disappeared and the freon took its place, but thats why I have gauges. my system said it take 32 ounces, should I charge by ounces or by pressure?

Yeah, PAG oil and mineral oil don't mix...However after killing two compressors with esther oil....I just decided to move to PAG oil. I actually used an AC flush, but didn't really like how it left things, so I ended up using brake cleaner. I removed all the parts from the car when I cleaned things up. For the compressor, I had a new compressor, and just drained the old oil out measuring the amount, and put that same amount of PAG back in.

Regarding the drier. There is dessicant in the drier, and at some point it will absorb all the moisture it can....then it won't work. It's hard to say when that is....so it's usually a good practice to replace the drier.

[fishbone79]

I'm completely converting my A/C system as well... I was wondering if anyone knew how much oil should go in the Zexel compressor / AC system? I'm switching from r-12 mineral to R-134a, so I've disassembled and flushed all the individual components (except the compressor just yet), replaced all the o-rings and the receiver/dryer. I need to put oil in the compressor and a little in the dryer, but I dont know how much... can anyone look this up for me?

Also, I'd like to use PAG oil rather than ester, but I've read a few cautions about flushing the compressor... Since PAG and mineral oil are immiscible, how do I get all the old mineral oil out of there, is it safe to drain it and flush it out with brake cleaner and compressed air? Is there a preferred method?

I've found about 50 threads regarding this conversion, but no one mentions explicitly flushing through their compressor or how much oil should be added. I have the vacuum pump and manifold, but I've never disassembled a system and flushed things individually.

[Legacy777]

Based on my thread
http://bbs.legacycentral.org/viewtopic.php?f=11&t=1083

I'd put about 5oz total in. 1 in the drier, and 4 in the compressor.

As for flushing the compressor, I have flushed a compressor, but that was one that died on me. Honestly, I would probably suggest flushing it with PAG oil so you're not doing away with any of the compressor's lubrication, but you're minimizing any remaining mineral oil. Then just drain it as best you can and then refill with proper amount of oil.

If you go that route, I'd suggest keeping track of the amount of oil you put in the compressor for flushing purposes, and how much that is drained out. That way you can kind of keep tabs of how much oil is in there, and know if there's oil that remaining in their after your flushing.

[fishbone79]

Thanks, Josh. I Saw your writeup, but I didn't know if those amounts were specific to the Calsonic AC system. I have the zexel, which I probably failed to note in my post. I'll try flushing it out with PAG.

[Legacy777]

I'd have to look at my Haynes AC book, but from what I found there was some differing in numbers, and I just split the difference. You should be alright with the 5oz