2015 Subaru Forester AC Compressor replacement

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Al9
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Re: 2015 Subaru Forester AC Compressor replacement

Postby Al9 » Sun May 24, 2020 8:17 am

I wouldn't charge so much oil through the refrigerant lines. This may end up starving the compressor of oil during startup.

When installing a compressor, the system's oil charge is usually poured inside the compressor (either suction port if there's no oil drain hole on the compressor's housing, or oil drain hole if the compressor has one), and then, before turning the AC system on, the compressor clutch hub (not the pulley; the compressor shaft has to turn) is manually rotated a few times (usually 10 times) once the compressor is attached to the lines, so to push any excess oil out of the compressor.

Other times, a certain oil quantity is put inside the compressor (and the clutch hub is still rotated before turning the AC on, in order to lubricate the compressor internals) and the rest is put into other parts of the system (condenser, evaporator, dryer for example).

Depends upon the compressor's manufacturer. But i've never ever seen compressor installation instructions instructing to load the entire system oil charge into the refrigerant lines and hence leave the compressor dry as a bone. Never. The compressor always has to have a good oil charge inside when first turning on. That's also why you have to keep the system's refrigerant charge at optimal levels. So that enough oil is always inside the compressor whenever it turns on.

Please thoroughly follow the compressor's installation manual's instructions if it comes with one. Properly oiling the compressor is a really really really critical thing.
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Cusser
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Re: 2015 Subaru Forester AC Compressor replacement

Postby Cusser » Sun May 24, 2020 8:37 am

I'm not an AC professional, but know "some".

1. I've used that aerosol can flush to backwards flush the lines on my own vehicles.

2. Always use brand new green refrigeration-compatible O-rings when assembling.

3. I add the oil to the compressor, then rotate with a socket at least 10 revolutions before starting the evacuation step.
nizzle321
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Re: 2015 Subaru Forester AC Compressor replacement

Postby nizzle321 » Wed May 27, 2020 3:39 pm

My AC Compressor installation is a case study in why you should seek out a knowledgable professional AC auto mechanic. Or, at the very least, do your research before jumping in. I've probably reduced the life of my compressor down to that of a $100 used one off of ebay with the shade tree mechanic monkeying around that I've done.

I did not read the last two posts before jumping in. Had I done so, I probably would have found the threaded cap on the bottom of the compressor that exposes what appears to be an oil reservoir. Instead of filling this, I emptied it in order to make sure the system was as close to empty as possible. Not my compressor, but same model (almost)... yellow box is the reservior cap I'm talking about:
Image

I tried to fill the AC system using the aforementioned technique of filling the yellow line with the system oil volume requirements. This was a fail because the yellow line is only open on one end. The oil will only go into the line at an extremely slow rate. I would have needed a syringe or similar and a half hour to let the oil drip in with this method. I used this method instead. https://www.youtube.com/watch?v=vGpM8va2XFg. I was careful to use the required amount of oil. The oil was drawn into the High side using the vacuum pump. So, the compressor probably made a few hundred revolutions before seeing that oil charge.

After Emptying the compressor, I put it back in. I Flushed out the condenser and what is probably the drier or a filter on the side of the condenser.
Here's a picture of my old condenser. Dryer/Filter element might be the canister welded to the left side of it.
Image
I meant to look at what is inside there but forgot. I regret not doing so now.This weekend I'll look inside of it and kick myself hard if I find some kind of porous filter material. The AC Flush can says to not flush out the filter or drier. Or expansion valve or compressor.

Then I removed the parts store TXV and used the remaining flushing solution to flush out the evaporator. I also Flushed out the lines. One of the lines was attached to the condenser, so that got flushed out with it. The high side line from the condenser to the TXV and the low side line from TXV to Compressor were flushed out separately. After flushing, with the flushing fluid, I used compressed shop air to force out the flushing fluid and help dry it.

The flushing solution came out clear after cleaning everything but the evaporator. The flushing solution that came out of the evaporator was oily for sure.

I put the oem txv back on with new o-rings. I reused the o-rings (they were only 1 week old) everywhere else. But cleaned and re-oiled all lines that get an o-ring.

After a vacuum leak pressure check and a 30+ minute evacuation, I pumped the oil in using the vacuum pump. Then I did another 30 minute evacuation. Then hooked the Refrigerant can up to the manifold and followed subaru's recharging procedure. After part of the 2nd 12 oz can was brought into the system, the compressor started to cycle on and off!

Unfortunately, now I have a low side low and high side high scenario. It was about 65 degrees outside when I was charging the system, which is below the lowest temp of 77 on subaru's pressure/temperature graph. At 77, I'm supposed to have 10-15 bar on the high side (HS) and 2-2.75 bar on the low side (LS) at 1500 rpm engine speed. At 1500 rpm, I was getting 16.5 - 18.5 bar HS and around 1.1 bar LS. At idle, I was getting 13-15 bar HS and 1.9 bar LS. With the AC Switched off, I saw 11.9 HS and 2.3 LS.

I'm now wondering if there could be something up with my OEM TXV. I watched a video of a AC pro diagnose an issue with a car and he found the TXV to be the issue. The HS and LS pressure was slow to equalize after turning the AC off. I looked at the pressures on my system after turning the engine off and it took 2 minutes for the HS to go from 15bar to 10 bar and the LS went from 2.2 to 3.1.

Any thoughts (other than stop screwing around and take it to a AC pro)?

I think I'll check my HS and LS again tomorrow to see if anything has changed. I don't think it would.

Thanks again.
tbirdtbird
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Re: 2015 Subaru Forester AC Compressor replacement

Postby tbirdtbird » Wed Jul 01, 2020 11:15 am

" I used compressed shop air to force out the flushing fluid and help dry it. "
This will introduce a lot of moisture from the compressor.
It has already been suggested that a 30 minute vacuum is insufficient, all the water vapor must be boiled off. We vac for a min. of one hr, and use a micron gauge. Once you have such a gauge in your hands you will realize that 30 min is a joke. Having said that, a commercial shop will give you a 20-30 min vac if you are lucky. The better the vac the better the AC works.
Two minutes to equalize on the TXV is not bad.
Vent temps are not being given.
It seems a lot of posters on this site do an end run around the suggestions made by the pros.
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Tim
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Re: 2015 Subaru Forester AC Compressor replacement

Postby Tim » Wed Jul 01, 2020 11:42 am

tbirdtbird wrote:"
It seems a lot of posters on this site do an end run around the suggestions made by the pros.


This is true for a few reasons. Doing it correctly is not a cheap or inexpensive way. In general, people don't like to hear sometimes their way is not the best.

I glanced through the comments above and just thought. Best of luck glad I don't have to warranty the parts. That may come off as being rude. Not intended. But the facts remain. Some errors in that approach.

We have had many successful repairs done through the advice from this site.
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nizzle321
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Re: 2015 Subaru Forester AC Compressor replacement

Postby nizzle321 » Wed Jul 01, 2020 1:36 pm

Not being rude. I realized I made several mistakes. Not my proudest moment.
I haven't read that a 30 min evacuation isn't enough.
There's a lot of conflicting information on the internet regarding AC system charging.
Is there a sticky in one of the forums on here that people new to AC repair can reference?
Dougflas
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Re: 2015 Subaru Forester AC Compressor replacement

Postby Dougflas » Wed Jul 01, 2020 1:48 pm

Evacuation and pulling a vacuum.... Most repair places only do a 20 minute to 30 minute vacuum because of the need to get the vehicle in and out the door. They can not tie the equipment up. Time is $$$ to them. Truthfully, most places do not have a micron gauge. If you can, pull a vacuum over night. The theory is to boil off any moisture. Moisture causes acid. Every vehicle I have ever owned has had the refrigerant recovered, a vacuum pulled with a micron gauge connected, and usually an overnight vacuum. All vehicles except the one I have now. It is R1234yf and I do not have the fittings nor expensive refrigerant.
When someone states they have pulled a 45 minute vacuum, I chuckle to myself. They have not done a thing. And I do not even want to talk about a marginal seal.
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Tim
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Re: 2015 Subaru Forester AC Compressor replacement

Postby Tim » Wed Jul 01, 2020 1:54 pm

nizzle321 wrote:Not being rude. I realized I made several mistakes. Not my proudest moment.
I haven't read that a 30 min evacuation isn't enough.
There's a lot of conflicting information on the internet regarding AC system charging.
Is there a sticky in one of the forums on here that people new to AC repair can reference?


I recommend this procedure as far as vacuum a system down.

1. Good Vacuum pump. Preferably a 5HP dual-stage.
2. Vacuum system for around 20 minutes or so. Close of gauges and turn the pump off. Allow the systems under vacuum to boil off moisture. Also, a good time to check and see if you have lost the vacuum. Do to a large or small leak.
3. Open gauges again and turn the pump[ back on for another 20- minutes or so.

4. Follow normal charging procedures.
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Al9
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Re: 2015 Subaru Forester AC Compressor replacement

Postby Al9 » Wed Jul 01, 2020 2:19 pm

Dougflas wrote:....the need to get the vehicle in and out the door. They can not tie the equipment up. Time is $$$ to them.

So true. To the point some of them do some serious damage without even realizing.

At least if double end capped PAG is used moisture won't bind to the oil.

Also, i've noticed in some patents that some kind of surfactant or corrosion inhibitor seems to be one part of the oil's additive package.
nizzle321
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Re: 2015 Subaru Forester AC Compressor replacement

Postby nizzle321 » Mon Jul 27, 2020 8:50 am

I am throwing in the towel. I gave it a go, but since this is my daily and I'm still a ways away from being a, even middling, AC DIY'er, I'm taking the foz to a qualified AC pro.

9 days ago I rented the AC manifold from Autozone again to check the pressure in my system. I didn't feel comfortable knowing the system was probably high. And I also wasn't too impressed with how cool it was. So I checked the high and low side pressures. They were both a little above the pressures specified by subaru. So I let a little refrigerant out in order to bring them into range. It worked. Or at least I thought. Driving home that night the air was barely cool. And I heard it making that low on refrigerant sound. In fear of wrecking my compressor, I stopped using the AC.

Subaru says in the service manual to drain refrigerant completely whenever adjusting the pressure in the system which probably explains why letting out some refrigerant was not the solution.

I'm not sure if I drain and recharge it if the High and Low pressures will fall into spec of if they'll end up high like before. I'm not sure if my TXV should be replaced. And the charging proceedur isn't clear to me. It says to charge it with the engine at 1500 rpm and the fan set to max but for inspection, says to check while idling the engine for 30 min and leaving fan at 3/4. Both inspection and charging reference the same pressure chart. There are just too many variables and I don't have the experience or stomach to keep messing with it. Maybe if this was my secondary or beater car. ....

Anyone following this mess recommend a AC pro in the Delaware or South East PA area?

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