AC flushing - to do or not to do

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

D

doru

Joined
Aug 13, 2021
Threads
45
Messages
1,205
Location
The Great PNW
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?
 
Last edited:
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.
 
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?
 
Last edited:
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.
 
You must log in or register to reply here.

Share this page

Back
Top Bottom