I'm trying to say that the cutting open the TXV method to make an adapter to flush is great if you're using liquid refrigerant on a flushing machine, but if you're using a flushing solvent from a can, it's probably not necessary or very helpful. I found that I had better results flushing each component individually with no hoses attached, as I was able to get higher air flow through the system to drain it.
Again, if you want to modify a TXV to act as an adapter so you can flush through the hoses that lead into the engine bay, great! It just may not be as beneficial if you're using solvent flush vs a flushing machine.

The FSM calls for flushing each component by itself.
So you are saying that your ' flushing solvent ' is not liquid ? I had assumed it was... thus would need a catch container when it came out...
You still need a way to connect on both ends of the evaporator ... without making special fittings you could use the Txvalve input and output hoses as ' funnel' and ' exhaust routing ' to catch basin.... after having cleaned THEM.... ?

If you're flushing each component by itself, I'd consider each hose to be a separate component.
No, the flushing solvent I used is a liquid. It is NOT liquid refrigerant though. Refrigerant would need to be held above a certain pressure in order to remain a liquid, which is why you'd need proper fittings to prevent leaks. With the solvent I used, a little bit of a leak where you inject it is not a big deal, though it can get messy obviously.

I AND the FSM consider each hose as a separate component...

So what is to keep you from Cleaning the INPUT hose... then attaching it to the ' emptied TXvalve' ... hold it up in the air and pouring any liquid flush into it..( effectively a long thin funnel ) .then applying a little pressure... as you described.... and letting the dirty flush liquid come out of the exhaust hose into a catch container... THEN removing that exhaust hose and cleaning it however ( both direction flush perhaps ) and then considering all the things having been ' individually ' cleaned ? Nothing.. it is just a matter of using what you have in a certain order for some convenience ...

I am not trying to argue with you. That would work fine too. My technique also worked quite well, and is less work. Either way is fine!

I am not arguing either... many can not visualize stuff like this...
and I am not understanding what you are using for a connection to the evaporator input and exhaust holes which would be more convenient than the use of the hoses...///emptied TXvalve...
Seems like something to direct the OUTBOUND dirty flush somewhere ' protected' ....like a big container is a nice and perhaps safer method ..... and use goggles no matter what system one is using...

Just came across this on AC fittings
http://www.meicorporation.com/pdfs/Fitt_Barb_Burga09.pdf

Of particular interest is Burgaclip hose and fittings which provides 74% less permeation rate. Anyone know anything about them, what year/ model uses them? Wonder if it is practical to retrofit into our old MB's?

Be aware that R-134A is being discontinued, though will be available for years via recovery. PAG oil absorbs moisture, so don't leave anything exposed long once you start. Read up on PAO 68 oil. No need to change the expansion valve, other than peace of mind. It adjusts to regulate evaporator temperature, not pressure, so "should work" for any refrigerant. Many older systems (GM?) even used a fixed orifice. Unless the compressor failed, not essential to solvent flush the condenser, but at least blow shop air thru it to get out most of the old oil.

http://www.carparts.com/classroom/ac1.htm

Most systems use the orifice tube system because it is cheaper... not better...
and I do not think it is the ' older system' relatively.... auto manufacturers changed to it to reduce costs... but introduced other problems as mentioned in the reference...

Well, besides passing the car onto him, I have replaced the injection pump and seals, replaced the vacuum pump, replaced the glow plugs, wire harness and module, replaced the headlights, and rebuilt the transmission.

One of the reasons we were really looking forward to getting the car for him was because it had good working air conditioning. Someone went to the trouble of custom-making a factory-looking parallel-flow condenser so it would work with R134a. It blew very cold for years.

Unfortunately, when my roommate took possession of the car, the air conditioning was only slightly cool. Then after the car sat while the transmission was out, the air was no longer cold.

My roommate took it to an air conditioning shop for a quick charge. The shop said that the system was empty because the suction hose and compressor were leaking. They wanted $2,000 just to get the system to hold refrigerant, then another $1,500 to fix the "Jerry-rigged fan wiring and non-operational dash vents".

So then the plan became to just replace the leaking hose and compressor and get it charged. But I decided to go the extra mile and remove all of the hoses so they could be rebuilt. Now it's looking like a can of worms.

I thought that the air conditioning shop was supposed to flush the system and add oil. I'm doing this on very limited time since I work long hours and have a long commute, plus a sleeping disorder where I don't feel right if I don't get 10-14 hours of sleep every day.

I might try doing a flush, but don't think I'll go as far as removing the evaporator. That is way too much time and we have to have this air conditioning working by next weekend before a friend flies in from out of state so he doesn't have to suffer being driven around in a hot car (like 110+F heat and 80% humidity).

My question about how good a friend was just with reference to potentially having to take apart the dash to deal with replacing the evaporator.... you really are working with limitations of time and accessibility... but as to specifically flushing the inside of the evaporator I think we did a good job of describing the accepted ( safest with regard to the threads ) method.. using the old Txvalve to connect to the evaporator and to the hoses which connect to it anyway.... cleaning the input hose and using it as funnel/flush holder while a little pressure is used to push the flush through.. and the exit hose to , in a controlled manner, direct where the dirty flush comes out into a catch basin of some type...

Yeah, I don't think I'll be removing the evaporator. Does the can of A/C flush work well using the hoses with the expansion valve attached? As in, the input hose isn't too long to where the flush can't reach the evaporator and pressurize it?

The new compressor supposedly is already filled with R134a oil, I think. I was wondering if it could be installed without having refrigerant in the system. I suppose it will be okay as long as the power wire to it is disconnected so it only runs on the nose bearings and doesn't spin the internal parts. I wonder if I should drain out all the oil in the new compressor before I install it.

I didn't know that you could "open" the expansion valve. How does one do this?

There is some pretty current thread where Funola has pictures of his Txvalve being taken apart..
This ' ac flush ' you speak of... is not familiar to me.. I only know of liquid bottles... but I think you are referring to a flush with ' built in pressure'.. of which I have no knowledge and even less confidence ... as I think sometimes repeat applications are needed to clean the object... then the last flush should be with a reserve of the clean liquid.....
I would drain the oil already in the compressor and add brand new out of a newly opened bottle of oil at the time you put oil into the system.... since you do not know how much exposure to moisture that has been exposed to..
I have no idea what you are talking about on the ' nose ' bearings only , etc...

It is hard to flush the evaporator through the expansion valve, unless you do what funola did by cutting an old one up and making it pass through so the flushing is done in the engine bay. Otherwise you have to remove the valve and flush the evaporator inside the cabin. You would need to connect a hose to the fitting and the other end in a container (like others have said). I have done it this way on a 123, and it is not a bad job if everything is covered and protected from the oil and flush solvent.

I found something interesting today. I got my new evap in (w123) and besides from having a couple big dents in the copper tubing on one end - which I plan on asking for a replacement evaporator for, I realized that it is plumbed with several circuits in parallel. I had assumed that it would be one long single circuit, but being set up in parallel makes me wonder how effective flushing clogs from it really is.
That being said, I dont believe there is any problem from flushing one, in fact the FSM specifies doing so, I believe. Just an observation I made.