Automotive Air Conditioning Information Forum

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 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.

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!

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.

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:


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.

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.

" 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.

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.

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?

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.

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.