I'm finally getting around to fixing the dual AC system in my 90 van. I went through all the fittings to find the exact O-ring sizes it needed, and to get at the two orifice tubes. Just for the record, the 1990 Aerostar with dual R12 system uses the red tube in the front and the brown tube in the rear. The numbers and sizes of rings it needs are 3 pairs of #6, 2 pairs of #8, 2 pairs of #10, and 2 pairs of #12. Plus the liquid line shut-off valve needs a #8 on one end and a #10 on the other.

It looks like I did have leaks after all, in 2 fittings. It's unfortunate that you can't tell ahead of time where they're going to show up. The system held vacuum when I last fixed it, but that would be at most negative 15 PSIg if I managed to pull a complete vacuum, so it's nothing compared to the 200+ PSIg (215+PSIa) of a fully operating system.

Another finding is that the front orifice tube has trapped some metal chips. I'm guessing that these must be from the compressor, and the cause of all the noise it's making. Fortunately, there is no black death that I can see; all the oil that leaked out when I pulled the lines apart seemed clean, and both orifice tubes show a little dirt, but no crud build up (besides the metal chips).

So I plan to flush out the lines, pull out the evaporators and condenser to flush them out on the bench. Should I get one of those liquid canisters with an air chuck, or can I just pour the flushing fluid into the components and use a regular air chuck to blow out the parts?

I was also wondering about the next vacuuming process. I wonder if I should somehow activate the rear shut-off valve when I'm vacuuming the system to make sure I get that part of the circuit.

 

unfortunately i can't answer your questions, however do you think it would be the same for a 93 with front and rear air that is set up for r12?

 

I'm sorry, would what be the same?

 

like same fittings and orifice tubes and such?

 

Yes, I'm almost certain that all the fittings and orifice tubes are the same for R12 systems across the different years. At least all the parts sources I've seen so far list them that way.

 

I did some search of the forum and could not find it just now.

Can someone remind me, how much oil I should put into a completely flushed dual AC system? I'm using mineral oil with HC based R12 replacement.

 

10 oz with aux. a/c

was the new compressor precharged with oil?

 

"New" compressor had a coat of oil on everything, but was otherwise empty. I turned it, and got nothing out of it. It makes a smooth "swooshing" sound, vs the crunchy grinding sound of my old one.

 

Pulled out both evaporator cores and condenser core this afternoon, and see something to give me pause. They are all parallel flow cores. So I wonder if it's possible to actually flush them, since the chance of cleaning out all the tubes by blowing pressurized fluid from the inlet/outlet is pretty low. I'm particularly concerned about the condenser core, since shrapnel has managed to travel through it to get trapped at the screen of the orifice tube.

Has anyone here flushed the cores before? Did you do a parallel tube core? How?

 

Ford developed and tried a method of flushing the FX10 systems but it worked poorly. Most dealers, for customer satisfaction and long system life, went to a total replacement repair.

i would recommend replacing both the evap. and cond., you've already got the expense of a compressor into system.

i would check interior of hoses especially on the high side for interior hose breakdown, common in high mileage high use older R12 systems, can make a swab ir use a pipe cleaner.

do you have an aux rear system? the rear hoses are a major collection point for system crud to settle out in, also replace the muffler filter cans.

Ford and most other auto manufs went to the plate/fin cond. because of the high efficiency of heat transfer

right from the horse's mouth

http://www.autoacsystems.com/fasttrack/condensers.html

The Condenser:
The A/C condenser performs pretty much the same function as an engine radiator, but the condenser cools the refrigerant (or freon) in the auto A/C system. Typically, the A/C condenser should be flushed to remove any debris. The flushing of the system will remove contaminated compressor oil and debris scattered throughout the system.
Auto A/C condenser designs are critical to the performance of your A/C system. Did you know that some condensers can not be flushed! In more current vehicle applications using high efficiency condensers, you should understand that they may not be able to be flushed. Why? The passages are simply too small and much of the debris gets lodged into the tube openings. In short, it's just impossible to remove all the debris from these condensers designs. The photo on the left shows a 'cut away' cross section of a typical high efficiency A/C condenser. You can see for yourself that the tube openings are extremely small.

SERVICE Required: Depending on the actual design of the A/C condenser, it may have to be replaced. If it can be flushed, it's best to use approved flushing agents that evaporate quickly and do not leave any residue in the A/C system. The ability to flush a condenser has to be considered on a case by case basis.

 

Great, so it looks like the only things I can flush in this system are the lines, and maybe not even the high side lines on the compressor output. I have an idea about how to get all the flushing agent out, but I am more concerned about getting trapped debris out.

Yes, I have the auxiliary (dual-air) system. The back end of the system was not used much during my ownership, and most parts do not have the same amount of dirty oil residues that I see in the front end parts. Maybe they're salvageable.

 

Just checked out Rockauto.com, and they show a few choices for condensers. I would like to get the Motorcraft part, but it says specifically "W/O Aux. AC". Were there 2 different condensers for with and without Aux. AC? It would make sense, as one would need a greater amount of heat dissipation than the other.

Since that model can't do it, I'm tempted to go for the really cheap Spectra Premium model, at just over half the price. They also have a pretty cheap front evaporator core. I hope they'll work well.

 

did any crud show up trapped in the rear orifice tube?
will tell alot about condition of rear unit

 

Nothing in the rear orifice tube. In fact, all the plumbing back there was pretty clean, vs the dirt found in the front parts.

Looks like that Motorcraft YJ215 condenser is made for 1986-1989 Aerostars, with just front AC. The later models all used the same different model condenser (Motrocraft YJ370?).

 

Ford made an a/c system change in 2/90
you probably need the Motorcraft YJ351 for late 90>95
look here for apps and part numbers
http://www.coldairfast.com/PDFs/cond...pplication.pdf
last i knew, FoMoCo MC condensers and evaps were made by Visteon.