AC flushing - to do or not to do

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D

doru

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The parts for my AC compressor replacement are in the mail, including condenser. I have to replace compressor due to a clutch problem damaging the compressor neck and in turn making the clutch slip (the AC computer detects slippage and shutoff the electromagnetic clutch).
I did not open the system, so I do not know what its inside state is.

I'm already replacing the condenser just to be safe although I have no reasons to believe it is bad.

Many places say to flush the system when replacing the compressor. The procedure is to use compressed air and a bottle of AC cleaner to force the cleaner though each system part after taking it off and try to evacuate as much of that cleaner before leaving the parts to dry before install.

I can see how this is useful if you take apart each part and do it so gravity is also helping you. My experience with blowing clear long/complex hoses using compressed air (I do use a moisture filter on my air supply) is that it never completely blows out all the fluid. Some small particles remain attached, especially if the hose is not straight. They disipate eventually but it takes time to dry. The AC pipes and hoses are not straight, and I'm not in the mood of taking the entire AC system apart and invite leaks in the system (there are no detected leaks of pressure problems for the short time the AC allows the compressor/clutch to run). Besides there is no way of doing the above with the evaporator, cooling box, valve, and their hoses and pipes (I'm not taking my dash apart). If I do it, they will have to remain in place.

What do you think, should I do it with the parts in place (except compressor and condenser/receiver/drier) or should I skip it entirely?
What is your experience with replacing the compressor?
 
I have flushed a system in place once and it worked well enough. But that’s the definition of an anecdote.

(Edit: I did take the system apart enough to get the expansion valve out at least)

IMO you don’t really have a choice. It is imperative to get the swarf from your failed compressor out of the system.. even if it means cutting corners on how you do it. Yes some particles may remain, but that’s part of the job of the drier.. to act as a filter to catch debris.

I’d suggest just flowing copious amounts of air to at least get as much of the solvent out as possible. And maybe judge your threshold for tearing the system open further on what you find actually coming out of it during the flush?
 
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Opening the System at all the Places to Flush is a Huge Risk to Introduce a Leak.
Add the PAG Oil to each Component & Change the Receiver/Dryer (Aluminum Can on Bumper) and System should be Conforming.
The Oil is Moisture Loving and Becomes Acidic if Exposed to Air for a Long Time.
Pulling a Vacuum on System Boils off the Moisture and Ensures System is Hermetically Sealed.
 
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Hornd said:
Opening the System at all the Places to Flush is a Huge Risk to Introduce a Leak.
Add the PAG Oil to each Component & Change the Receiver/Dryer (Aluminum Can on Bumper) and System should be Conforming.
The Oil is Moisture Loving and Becomes Acidic if Exposed to Air for a Long Time.
Pulling a Vacuum on System Boils off the Moisture and Ensures System is Hermetically Sealed.
*Use Mineral Oil on all O-Rings installed.
Click to expand...

I recommend DO NOT use mineral oil on components used with an R134a system. Use the PAG oil for the o-rings.
 
I looked more in FSM and the things are more complicated. There are two evaporators and two expansion valves in LX, one pair for AC and one for cool box.
It looks like none of valves are easy to access. @bloc said he removed the valve (I assume that it the AC one as I do not think the 13 LC has the cool box) but how easy is to get to it?
[Edit] there are 3 pairs. I missed the rear evaporator and valve.

Even if I remove the AC valve, I still have the cool box & rear one to deal with and if not, it will block the flushing. The last thing I want is flushing fluid left over inside the system.

I'm leaning more and more on not doing the flush. In that case the question becomes how much oil do I need to leave in the new compressor (it comes filled with oil for the entire system). I can use the FSM/Denso procedure, but that accounts only for compressor replacement. In my case I'm also replacing the condenser.
How do I figure out how much oil I need to leave in the compressor to account for the condenser?
 
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Sorry I wasn’t clear, the vehicle I flushed wasn’t a Landcruiser or even a Toyota.

Also the 13LC does have a cool box so yes same amount of components to take into consideration.
 
When I got my new compressor it says to flush for the warranty. Assuming you are replacing it due to an internal failure that would cause metal to go into the system. If you are replacing just for the clutch failing I personally don’t see the need for it. I’m pretty sure you would need to pull the evaporators and expansion valves to do a proper flush.
 
I have worked on a lot of automotive A/C systems and my personal "opinion" is don't do anything that doesn't need done.

If you didn't have an internal compressor failure, you have no reason to flush your system or even replace the condenser. Measure how much oil drains out of the compressor you remove and have at least the same amount back in the new one. Too much oil isn't good so handle the capacity as you feel is appropriate.

New o-ring seals are always appropriate with some of the same oil on them.

Do what let's you sleep at night, but no way my employer would require me to change good parts or flush what doesn't need flushed and we had to warranty the work.

Just my personal opinion. Good luck with whatever you decide.
Scott in AZ.
 
I got a Toyota condenser and there is nothing besides the condenser in the box. It has rubber plugs on both ports. No idea if the oil is inside.

But if it comes with oil then that is not what Denso manual says. Denso is saying that the new compressor has all the oil needed for the entire system if the system is new or flushed.

FSM doesn't mention anything about adding, measuring, or draining oil from condenser. FSM mentions that the compressor should be run for 5min before refrigerant evacuation so oil is collecting in the compressor.
 
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GrouchyTech said:
I recommend DO NOT use mineral oil on components used with an R134a system. Use the PAG oil for the o-rings.
Click to expand...
You are Correct.

Mineral Oil was for R12 Systems and not to be Used on Green O Rings with R134A.

I will delete that Statement so no one is Confused - Thanks for Clarity.

R-12 Systems: Mineral oil is the standard lubricant for older R-12 systems and is safe to use on their O-rings.

R-134a Systems: Mineral oil is largely incompatible with R-134a refrigerant. You should lubricate these O-rings exclusively with PAG (Polyalkylene Glycol) oil.
 
The majority of the oil does stay in the compressor. It does circulate through the system and some accumulates in the other components and coats the entire system. Unless you flush the entire system out completely, you will never know "exactly" what you have.

IF ...it was my truck and I knew for sure the system has never been into. And I need to just replace my compressor because of the clutch and NOT an internal failure, I would measure what drained out of the old compressor and see how much the recovery machine caught. Then add that much back. Especially if it was working fine before the clutch failed.

Your truck and money so your decision. Just throwing one opinion your way. Git'r done, it's HOT.
Scott in AZ
 
I'm not a shop sand I don't have a recovery machine nor am I familiar with how it operates. I'm going to have that done for free at a local shop. Is there a way to know how much oil the machine is catching? Is that info something the operator can easily tell me?
 
Yes, trying to get it done but silly me ordered the compressor from Toyota and that version doesn't come with the clutch, like Denso one. Waiting now for the clutch to arrive.
Lesson learned and advise for others... buy the Denso compressor version not the Toyota one. You save few hundreds and labor to assembly and adjust the gap. The compressors are the same, both made by Denso.
 
Sorry about your struggles. Frustrating situation for sure. The recovery machines I have used collected whatever oil came out with the refrigerant in a graduated container so you knew how much. It's been years so I would think the newer equipment would be even better.

I based my opinion on your original post where you really don't want to take the entire system apart and or tear the dash apart and in this situation I agree with you. It's not like you have an internally trashed system. You didn't mention leaks or poor performance, just a failed clutch.

There should be nothing wrong with any other parts. If you didn't open the system to the atmosphere, there's no contamination. The big question is how much oil to add. Ideally , the same amount you removed. Too much is bad, too little can be bad depending on how much. It doesn't have to be perfect. Yes, the shop evacuating the system should be able give you a more specific recommendation. I hope they take care of you and get you going again.
 
Somewhere I had a list of how many ounces each Component was to get in Ounces.
I'm sure a Google Search can Provide the List.
You Replaced the Receiver/Dryer?
They are Cheap (~$20) and the Desiccant is likely Saturated which makes the oil Acidic.
 
Hornd said:
Somewhere I had a list of how many ounces each Component was to get in Ounces.
I'm sure a Google Search can Provide the List.
You Replaced the Receiver/Dryer?
They are Cheap (~$20) and the Desiccant is likely Saturated which makes the oil Acidic.
Click to expand...
Definitely replace the dryer.
 
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