A few days ago I went out to get in my 82 240D, I noted a puddle of clear oil that had run out from under the car. Note that my garage floor was constructed so that liquid runs toward the house and not out the garage door, which is another story. After verifying that all vital fluid levels were fine, I determined it was the A/C system oil I was seeing. The A/C cooling temperature began to deteriorate over the next couple of days and finally the compressor wouldn't kick on at all (obviously a major leak). I recently converted the system from 134A to Duracool.

I tried to pinpoint where the leak was coming from, but all I could really determine was that it appeared to be dripping off of the compressor.

The question is how do you determine the source of a major leak? I suspect the compressor, but it certainly gave no advanced warning. After I did the Duracool conversion, I was getting about 45PSI suction pressure and 48 degrees out the vents. The system did still appear to be using way to much horsepower, but the car has always been considerably slower with the A/C on with R12, 134A, or Duracool. I was hoping that the Duracool would improve performance, but I really didn't detect much improvement. When I converted from R12 to 134A a couple years ago, all I did was evacuate, charge with 134A, and add a can of 134A oil.

Do I have to re-charge it to find the leak? Or is there another way?

__________________
1976 240D
1987 560SL
2007 E320 Bluetec
1998 C280 (now son’s car)
1982 240D Manual - Sold

My suggestion- recharge, put a green dye that you can see or red if you prefer that, let it run and you will see the leak. But you will have to recharge so that compressor kicks in. Use a dye that does not need UV light and special glasses to see it.
Some folks might suggest you to bypass the pressure switch and get the compressor to kick in with whatever you have left in there. But I am not so sure if I would want to do that.

MVK

__________________
One penny saved is three penny earned.

1985 300D Turbo 179,000miles

This is interesting that this system has had multiple conversions. I hope that the system was THOROUGHLY flushed when converting from 134 to DuraCool. If it was not thoroughly flushed and the correct and right amount of oil put in the system, I feel quite sure that this is what led to your problem. The problem likely being compressor failure.

DuraCool is not one that shows up on the list of SNAP evaluated alternate refrigerants, (at least not the list that I have) so I can't tell what is in it. But, I suspect that whatever it is, unless you flushed all the oil, there was a strange combination of oil that may have led to compressor failure.

I think MVK offers the most practical approach, charge the system with dye, I would recommend UV dye, then run it and search for the leak with a black light. You will be able to see everything in the system with the black light except the evaporator, to check it, use the black light to look for UV dye in the condensation water that drains underneath the car.

My guess is that you will not get it to cool enough to get any evaporator condensation.

If the compressor did indeed fail, you really have some work on your hands. You will need to replace the compressor (use a new one, don't waste your money on a rebuilt R4) flush all lines, the condensor and the evaporator THOROUGHLY, replace the filter-drier and preferrably find a suction side filter for the compressor inlet. There are some companies that sell a screen that you can put inexpensively in the inlet to the compressor. Pump the system down THOROUGHLY to remove moisture AND the flushing agent.

Unless you can find out more about the DuraCool, I would recommend going back to R12 if you really want to have a proper performing AC, or r134 if you want refrigerant economy. The 123 cars just don't convert well. R12 is coming down in price due to decreasing demand. I would highly recommend that you go back to it if you plan on keeping the car.

I sympathize with your problem, I've been there, done that. That's why I know NOT to use a rebuilt R4. Summer in the South with no AC is not fun.

Best of luck,

Before you start any leak finding procedures it is really helpful to really clean the engine compartment.

Although I'm nowhere near the A/C guru he is, I agree w/ Larry Bible. Duracool is of those hydrocarbon refrigerants - not approved by the EPA for use in motor vehicles. Your problem could trace back to your first conversion if the flush that Larry mentioned wasn't done. Moisture in the system can combine w/ the refrigerant to form acids that eat out the compressor seals. The dye test should reveal all, and if the compressor is shot consider R-12 again - its around $30 a can here, and I understand some places have it for $15.

Good Luck.

__________________
Tjohn

82 300 SD
77 450 SL (gone)

I don't know if DuraCool is a flammable or not. If it is, it is illegal.

IF the compressor indeed is gone, I expect that the original conversion to r134 is what sent the compressor on its way. By only evacuating and adding a 'can" of r134 oil, there is no telling what kind of oil was in the can. Most of the r134 cans that have refrigerant AND oil contain PAG. PAG does not mix well with mineral oil.

Good luck,

Thanks everyone...this is a great help to my knowledge vacuum.

When I converted to 134A I followed the directions on the conversion kit that I bought. At the time the system was low on R12 and I did not have a source at any cost for R12 without taking it to a shop. I evacuated the system and added refrigerant and oil per the instructions (as I recall flushing was not mentioned - or was mentioned as optional). Since then the system has needed a can of 134A before each cooling season, and so there must be a slow leak (I think this is the third year). When I converted to Duracool I added no oil, again, following their instructions, as it is supposed to be compatible with 134A or R12 oils.

As mentioned, it seems to me that the compressor has been laboring even more so this summer. Also, when I check the low side pressure I would see greenish oil oozing out of the system. The amount of oil on the floor was suprising to me. I am wondering if this system had way too much oil in it, and since the compressor is the low point in the system, it was literally oil logged. I am no A/C expert, but from my industrial experience, I know that liquid levels in centrifugal compressors are fatal. The R4 looks to be some type of rotary or centrifugal compressor as opposed to the York, which appears to be a reciprocating unit.

A couple of other questions.....Performance Products recommends changing the expansion valve when changing the Compressor. Where is the expansion valve located in these systems? Flushing the system sounds difficult, because it would seem that you would have to pump or pressure the flush through the system? Removing the expansion valve would seem to be a help since it would be major restriction in the system (dividing line between the high and low side)? So you could flush from the expansion valve to compressor suction and from expansion valve to compressor discharge (or vice versa)? I noticed that JC Whitney sells a flusher for about $50 bucks that works with air pressure to force flush through A/C systems....am I going to need something like this? Could you use something like the pressure brake bleeder that I saw on this forum (a converted garden sprayer)?

I am in no rush to get this fixed. I work in an office all day that is way too cold, and I really haven't missed the A/C on the 20 minute drive home everyday (don't need it in the morning at all). So I am going to take my time and get my ducks in a row, before I tackle the project....even though I know that August and September are hot months in Alabama! Thanks for the help...you guys are a great bunch to be associated with.

__________________
1976 240D
1987 560SL
2007 E320 Bluetec
1998 C280 (now son’s car)
1982 240D Manual - Sold

The expansion valve is a block at the evaporator inlet/outlet basically underneath/behind the glove box. A flush gun works very good and does indeed cost about $50. I would try to find a local automotive air conditioning supply. Most communities have someone who does mobile AC repair AND sells parts. They usually are a good source of advice and parts/supplies that you need.

I would recommend removing the compressor, disconnecting all lines including; condensor, evaporator (this is diconnected when you remove the expansion valve) and the filter drier at the right front corner of the engine compartment. Fill your flush gun with flush and blow some flush through each unit, then blow it out with compressed air. Put in the new filter/drier, use green o-rings and nylog o-ring lubricant on them. Pour out as much oil as you can get from the NEW compressor. Prop it up in a pan and let the oil run out while you are doing all the flushing. Then pour in the correct amount (I think it is 6 oz.) of Ester oil, bolt the manifold in place on the compressor BEFORE securing the lines to brackets above the compressor. Then evacuate for at least 30 minutes with a good vacuum pump, but a longer time of evacuation is better. Then charge system with r134.

What I would consider even better would be to follow above steps except use mineral oil and R12. If you do this you should put UV dye in when you charge so that if a leak remains, you can find it when you have to recharge.

R12 has come down in cost and would give you a much better air conditioner.

I would suggest going to aircondition.com and surfing around in there. One of their advertisers has a good book on automotive refrigeration that would be well worth the $15 or so.

Best of luck,

On the flushing,,,, some guns use a gravity liquid flow system powered by an air compressor, like the new top tank paint guns which are hvlp..... some have a tank which pressurizes the liquid with an air compressor then forces it through when you pull the trigger..

These are going to produce very different flushing actions...I prefer the one which flows faster,,,the "put in some" fluid and lots of air to move it though the system .

When I have a chance, ie, the item is able to be handled... I put in flush ,hold my fingers over each end and slosh it around every which direction as if I were cleaning a gas tank... then through flush several times...

Something which is not mentioned is that you should be monitoring what does or does not come out of the end of the item you are flushing.. this is not one of those automatic, or perfunctory deals.. you are trying to be sure the item is clean... I always put clean white cheescloth type material on the end of hoses so I can inspect what is being blown out.. and I keep flushing until it is totally clean fluid coming out...

aircondition.com or acsource has some good instructions and one of them mentions multiple flushing BOTH directions . Being compulsive obsessive about the cleanliness of the inside of an ac system I naturally believe this advice

I am going to make a catch container for my flush which will allow inspection of the flush AND allow me to reuse it... (on that particular job).

The factory shop manual says to take out the old expansion valve and keep it to use as a tool in the future,,, but I have not exactly figured out the manner of converting it except they say take out the stuff from that end hole... anyone know the answer on this deal ? Does the area between the two main opposite flow channels need to be sealed ? Which operations are able to be performed when this converted expansion (actully a combination valve) is used ? They are referring to the combination valve because they show a picture of it to show what to take out... It COULD provide a place to hook up a flush gun for the evaporator and the two hoses running forward....

Leathermang,

Where is the expansion valve? I don't see it? From the Performance Products Catalogue the part looks fairly small with screwed threads on one end and flange attachement at the other end. Perhaps it fastens to the evaporator and to a hose? It would be nice to figure out a way to flush right through the evaporator, without having openings inside the passenger compartment. (sounds like a potential mess or major surgery in taking everything apart??)

__________________
1976 240D
1987 560SL
2007 E320 Bluetec
1998 C280 (now son’s car)
1982 240D Manual - Sold

As I said at the beginning of my post above, the expansion valve is on the evaporator behind/below the glove box. Remove the passenger side kick panel. It is a rectangular prism roughly the size of a pack of cigarettes, and should be wrapped with gooey rubber refrigeration system insulating tape.

Good luck,

LOL, it really is right where Larry said as far as I know of your car... my 81 300td and my 240 1980 have it the same place...that is pretty much directly under the left inside of the glove box. But you access it by taking off the single panel under the glove box...right above your feet.
It has four lines going to it in one plane...it should be bright metal colored...on the left side it has a flat bulb used for sensing temp... on the inside of the valve... on the end I think it has a plug... that is the opposite side from the flat copper looking disc... the other lines are on the top and bottom and have 17,19 20 and 24 mm flare fittings on metal lines ( if memory serves ). The flow is down on the right side and up on the left side... so the temp and pressure on one side can be effected by the valve or rod which goes between the two sides from the copper disc to the plug...IT is pretty solidly mounted , with that many metal lines.. however , if they are very tight then you will want to hold the body with an adjustable wrench... of course you should just get each one loose and leave in place until all are loose... then take them off,,, that may preclude you needing to use the adjustable wrench... Caution : I can not think of a less pleasant place to try to refit metal lines that are screwed up.. so be gentle.... fair warning ! Greg

It is kinda tight with respect to the lines being close to each other on the valve.. however, the placement of the valve in terms of access is very nice.

If you take the old valve and turn it into a fitting for flushing then you could run lines long enough to reach out the door .... but secure the end so it does not whip around and douse you with flush...

Duh, this was already in my computer...

Attached Thumbnails

 

You will definitely want to route the flush outside the door and leave the routing in place while you blow out the flush, most important.

Also when you're done it should not look like leathermang's, his has the insulation tape off of it for service. When finished use gooey insulation tape over it for it to work properly.

Good luck,

This one did not have that tape when I started working on it.. but my parts wagon had lots of it so I am using that when going back together.. however , I was going to ask you about where you meant it needed to be... the wagon only had it on both the lower metal hoses... but it sounded like you meant the entire combo valve should be gooey wrapped.. is that correct ? Thanks, Greg