2015 Subaru Forester AC Compressor replacement

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nizzle321
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Re: 2015 Subaru Forester AC Compressor replacement

Postby nizzle321 » Wed Apr 22, 2020 7:37 pm

According to Subaru's service manual, I should use a electronic leak detector. So I should indeed charge the system first.

I did a quick search. There doesn't appear to be a electronic leak detector for borrow from Advance Autoparts or Autozone. Are there any online vendors that have them for rent?

It also seems to be kinda silly to do this with my known defective compressor. I think I should instead use the new compressor and check for leaks right away. I don't think it will be a big leak, so don't need to worry about starving the brand new compressor of oil.
Al9
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Re: 2015 Subaru Forester AC Compressor replacement

Postby Al9 » Thu Apr 23, 2020 2:10 am

No need to waste refrigerant. Carefully looking at all the lines and AC components in search for anything oily could do the trick. I once found a leaking o-ring behind the expansion valve by myself. Jamming a piece of weatherstrip foam between the TXV and its insert in the firewall and then retrieving it after some time (months in my case, since it was a really slow leak) did the trick. Left a clear trace of green dye (already had dye inside). I'd entrust it to a professional for a serious leak test though. Personally i'm against using refrigerant for leak tests. I think that pros use some kind of inert gas to detect leaks.
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Re: 2015 Subaru Forester AC Compressor replacement

Postby Tim » Thu Apr 23, 2020 6:55 am

Nitrogen with a little R134a works fine for leak checks. Personal preference on using either a electric or a dye style leak detection option.
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nizzle321
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Re: 2015 Subaru Forester AC Compressor replacement

Postby nizzle321 » Sun May 17, 2020 9:56 pm

I need some help. When I turn the AC on, the compressor turns but never turns off. And the air isn't cold. Maybe slightly cooler than ambient. The high and low pressure line fittings get warm to too hot to touch. And none of the lines get too cold to touch.

I replaced the following:
- compressor,
- condensor,
- expansion valve,
- and all the o-rings in the lines connecting those parts
- Serpentine belt

Everything went together pretty nicely. I followed subaru's instruction and made sure the new o-rings were gunk free and had a nice coating of the refrigerant oil before inserting. The lines and expansion valve were torqued to spec.

my dad and I followed subaru's refrigerant charging procedure for my forester. We did the following:
- open both high and low side on AC gauge manifold and run a vacuum for 5 min or until it reaches -14 psi, stop, and wait 10 min.
- Check for leaks. No leaks.
- Continued the evacuation for 30 minutes to get the air and moisture out.
- close both high and low side valves

Then since it was diner time, we let it sit for 2 or so hours. Went back and the gauges were still both pegged at their minimum value. No leaks.

After removing the vacuum from the feed line, we tapped the one container of refrigerant. I had two containers of R134A, each with 12 oz of R134A in them. Both are several years old.

Continuing from the service manual, we;
- hooked up the can of R134 to the feed line
- open valve on can
- purge air and moisture out of feed line.
- Open low and high side valves to allow system to fill.
- check low pressure gauge. if at 2bar, close high and low valves.
- with low and high side valves closed, start the engine
- set the AC up w/the following settings;
- Max cold, max fans, vent
- bring engine rpm to 1500 rpm.
- Open the low side valve and allow it to fill with refrigerant until it reaches the specified amount.
Looking at the table provided, It gives a high side pressure between 10 and 15 bar and a low side pressure between 20 and 28 bar (for the ambient temperature of 77 F). Note, it was only 60-65 out when we were doing this.

Here's where things get confusing for me.
ON the first 12 oz can, the pressures went higher than spec on the high side. THis indicates that it was over filled. But I didn't use even a full 12 ounces of refrigerant. And the compressor just stayed on... as long as the AC was set to be on, the compressor's clutch stayed engaged. And that's when the line in and out of the compressor get really hot.

w/the valves closed and engine off, I let a little R134 out at the high side. The reading on the valve went down a little bit. So we turned the car back on. No change. compressor still runs forever. And no cold air is blown and the lines get really hot.

Going on what my dad thinks, that the system doesn't have enough refrigerant, we tapped the other can of R134, purged the air, opened the low side valve, and turned the car on. I let as much refrigerant in to bring the high side up to the maximum. This took a few seconds at most.

No change. Fittings still get really hot and clutch never disengages.

Please help if you can.

Thank again!
Last edited by nizzle321 on Mon May 18, 2020 7:05 am, edited 1 time in total.
Al9
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Re: 2015 Subaru Forester AC Compressor replacement

Postby Al9 » Mon May 18, 2020 5:07 am

Can't really say anything except that i really hate when AC tries to make you go insane. I'm sorry your efforts haven't let you to your ice cold AC paradise yet. I'd have paid a pro to vacuum and recharge through a RRR station if i were you. So to rule out any possible charge issues. Now i don't think this is an overcharge, or your compressor clutch would have cycled like mad instead of staying on. But everything is possible. That evaporator is definitely not getting cold or its thermistor would have cycled the clutch off eventually (again, i know modern TXVs are set up to let the evaporator pressure and temperature decrease as gently as possible with low heat loads and avoid as much clutch cycling as possible; this will never cycle off and on as often as an ordinary orifice tube system would do).

Again, i really hate when an AC system does everything it can to turn a man insane.
nizzle321
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Re: 2015 Subaru Forester AC Compressor replacement

Postby nizzle321 » Mon May 18, 2020 9:07 am

Al9 wrote:Can't really say anything except that i really hate when AC tries to make you go insane. I'm sorry your efforts haven't let you to your ice cold AC paradise yet. I'd have paid a pro to vacuum and recharge through a RRR station if i were you. So to rule out any possible charge issues. Now i don't think this is an overcharge, or your compressor clutch would have cycled like mad instead of staying on. But everything is possible. That evaporator is definitely not getting cold or its thermistor would have cycled the clutch off eventually (again, i know modern TXVs are set up to let the evaporator pressure and temperature decrease as gently as possible with low heat loads and avoid as much clutch cycling as possible; this will never cycle off and on as often as an ordinary orifice tube system would do).

Again, i really hate when an AC system does everything it can to turn a man insane.


Well, I felt really good about how things were going up to the point when I started my forester and got Those mixed signals from what the gauges said and the lack of refrigerant going into the system and the lack of change in air temp.
And before I attempted this, I read through all the recharge procedure steps and it all looked very straight forward. On top of that, I had a vacuum pump and manifold gauge set already. I didn't have to buy anything. Except I did have to buy a new vacuum pump because the old one I have is not working. If I knew I had to buy a new vacuum and new gauges, I probably would have considered going to a professional. ON the other hand, I do take pride in doing most of the repairs on my cars myself. Yea, I'm a complete AC Newb. Yea, maybe I should have known better.
I'm wondering if my manifold set is bad... It doesn't seem like it is. Before doing anything with refrigerant, I made sure it was measuring the pressure in the system and that I had a feel for how it responded to valve opening/closing as well as the purge and all the fittings.

I did not attempt to flush my evaporator out.

I should note, I used a OEM subaru compressor (latest model) and UAC brand expansion valve, O-ring kit, and pacific best brand condenser. One extra thing to note, Rockauto sells two UAC expansion valves for my forester. A "from 5/1/2015" and a "to 5/1/2015" model. I bought the "to 5/1/2015" one... 2016 and newer foresters are specd with the "from 5/1/15" ones. I wonder if this has anything to do with it. Maybe I should put my old expansion valve back in and see if that works.

I'll check one more time this afternoon and then head to an AC professional I guess.
Al9
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Re: 2015 Subaru Forester AC Compressor replacement

Postby Al9 » Mon May 18, 2020 10:25 am

nizzle321 wrote:I did not attempt to flush my evaporator out.

Bad. Always better to start with a fresh system oil charge (either inside the comp, or inside the comp plus other parts such as the condenser and evaporator) rather than attempt to balance oil.

nizzle321 wrote:I should note, I used a OEM subaru compressor (latest model) and UAC brand expansion valve

Not saying that UAC sells bad parts, but their TXVs are really cheap IMHO. Personally the TXV is something i would definitely never cheap on. Either Denso or OEM, even second hand if it looks clean enough. What a TXV does is of utmost importance - makes sure your compressor never runs out of lube, makes sure not too much liquid refrigerant goes back to the compressor, tries to stop the evaporator from freezing up (not saying that it will outright stop an evaporator from freezing up if you turn the blower fan off and somewhat tamper with the evaporator temperature sensor, but a cross charged TXV will actually try its best to keep the suction pressure from falling down too fast), meters how much refrigerant goes inside the evaporator. Not enough refrigerant going through? Bad. Too much refrigerant going through? Bad. I would cheap on every other AC system part, even the compressor's oil (as long as it's double end capped PAG or, whenever required, non-conductive Ester, no need for OEM oils), except the TXV.
nizzle321
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Re: 2015 Subaru Forester AC Compressor replacement

Postby nizzle321 » Tue May 19, 2020 12:21 pm

Al9 wrote:
nizzle321 wrote:I did not attempt to flush my evaporator out.

Bad. Always better to start with a fresh system oil charge (either inside the comp, or inside the comp plus other parts such as the condenser and evaporator) rather than attempt to balance oil.


Damn... Is it too late to do this? My compressor came with the oil needed for the system. Since attempting to charge the system, will the compressor have oiled the entire system with the oil that is in it? I know you're supposed to measure the oil that is in any component that you replace and put that much oil back in, but in this case, you can't measure the oil in the evaporator since you flush it out.

Al9 wrote:
nizzle321 wrote:I should note, I used a OEM subaru compressor (latest model) and UAC brand expansion valve

Not saying that UAC sells bad parts, but their TXVs are really cheap IMHO. Personally the TXV is something i would definitely never cheap on. Either Denso or OEM, even second hand if it looks clean enough. What a TXV does is of utmost importance - makes sure your compressor never runs out of lube, makes sure not too much liquid refrigerant goes back to the compressor, tries to stop the evaporator from freezing up (not saying that it will outright stop an evaporator from freezing up if you turn the blower fan off and somewhat tamper with the evaporator temperature sensor, but a cross charged TXV will actually try its best to keep the suction pressure from falling down too fast), meters how much refrigerant goes inside the evaporator. Not enough refrigerant going through? Bad. Too much refrigerant going through? Bad. I would cheap on every other AC system part, even the compressor's oil (as long as it's double end capped PAG or, whenever required, non-conductive Ester, no need for OEM oils), except the TXV.


I didn't know the TXV was something that the parts store brands could get wrong. My car was manufactured in 2014, so I definitely got the correct one for my car... That being said, should I put my OEM one back in? It has the same 5 years of use as the condenser and compressor that I replaced.
I also bought UAC PAG100 oil. But, since the compressor comes w/the oil needed, I didn't use it (other than for lubricating the o-rings - per Subaru's service manual).

I would like to give this another shot on my own before I throw in the towel and take it to a AC Pro. I would like to flush the evaporator, clean up and stick the OE TXV in, and try again. I'm wondering if my manifold set's gauges are no longer providing accurate readings. If it reads a lot higher pressure than it really is, that could explain everything. I don't think a bad TXV would cause the pressure to read high on the high side. A new AC Manifold gauge set is $50-$100 more dollars but I just spent $90 on the vacuum...

Thanks again.
Al9
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Re: 2015 Subaru Forester AC Compressor replacement

Postby Al9 » Wed May 20, 2020 4:02 am

nizzle321 wrote:Damn... Is it too late to do this? My compressor came with the oil needed for the system. Since attempting to charge the system, will the compressor have oiled the entire system with the oil that is in it? I know you're supposed to measure the oil that is in any component that you replace and put that much oil back in, but in this case, you can't measure the oil in the evaporator since you flush it out.

Bad. If you're not flushing the entire system when you're replacing the compressor, you're supposed to read the refrigerant oil table in the service manual and remove oil accounting for the component/components you didn't either replace or flush (that is, if your car's service manual tells you to refill 1 fl oz oil whenever the evaporator is replaced, and the evaporator is the only part you aren't replacing or flushing, right before installing a compressor that has been filled with the normal system oil charge you would have to drain this 1 fl oz of oil from it, and then add the oil quantity that was recovered during refrigerant recovery; that's the oil balance). Doing that is still a risky choice, because the oil quantity listed in the table for a specific component is only the quantity supposed to settle in that component in normal operating conditions, so the full system flush is always the best option whenever possible. If you've ran the system with a very low refrigerant charge inside, most of the system oil charge will settle within the evaporator where refrigerant velocities decrease the most, and it will likely be much more than the 1 fl oz example. You could possibly have an oil overcharge now. A very bad thing since the compressor's label lists an 80cc oil system charge. Proper oil quantity is really critical with your system.
nizzle321
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Re: 2015 Subaru Forester AC Compressor replacement

Postby nizzle321 » Sun May 24, 2020 7:59 am

I'm going to give this one more shot.

I will flush all the components out. I bought two cans of this: https://www.autozone.com/a-c-charging-a ... z/896840_0
Hopefully I only need one can.

Autozone also has a manifold gauge set you can borrow so I borrowed that.

And I bought another two cans of R134A.

I will flush the condenser, evaporator, and lines. I doubt I'll get anything out of it, but I will try to drain the new compressor of oil as well. This way, when I finally add the oil, I'll be as close to having the correct amount of oil as possible.

I'm going to put my OEM TXV back in. I don't think there is anything wrong with my OEM TXV and, after seeing how finely manufactured and calibrated they are, I am heeding your warnings. Since my o-ring kit came with a lot of extra o-rings, I'll replace the o-rings that mate to the TXV yet again.

When I'm ready to go, I'll add the 80ml of oil that the system requires to the yellow line that the refrigerant can hooks up to. This will bring the refrigerant into the system during the charging process.

That's that... The hardest thing will be the flushing process. I have to figure out some rigging so I don't make a mess. And so I don't mess up the o-rings.

I'll let you know how it goes!

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