Car: 1991 560 SEL with R12 system with a working compressor
Problem: A/C not very cold.
Test: injected UV dye with additional Freon

Upon putting a blacklight on the compressor, I found it is totally covered by the yellowish dye. I mean the whole compressor lights up like some one painted it one side with this UV dye. I am going to spend some more time tonight to study the leak a bit more and I need your advise.

How should I go about checking if the dye is just from the connectors on top of the compressor? What could explain the fact of large area of even dye deposit?

Thank you.

Probably the o-rings that seal the hose manifold to the compressor.

Dye is all over the engine side, right? comes around to the bottom and crawling up the fender side?

Leak test, likely the two 0-rings are shot, blowing freon and oil out. Naturally, it's almost impossible to reach the engine side to test, and you will have to pull the compressor to replace them, but otherwise this is a very easy job. You won't have to pull the clutch or anything, just the hose maifold (four 6mm allen screws, probably). Get new 0-rings for the hose connection too, just to be safe.

Peter

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

How long ago did you put in the dye? Oil has a tendency to migrate along surfaces. If you're still unsure of the origin, see if you can wash it off and try to catch it earlier next time.

__________________
95 E320 Cabriolet, 159K

Warm water and a gel shampoo .. 50/50 mix ..
Whip the mix up real good with a 1' paint brush and apply the foam to the head of the compressor..
You will see the leak as it will blow out a bubble as large as an orange..

Kids Bubble mix works well too.
They make leak spotter liquids , but I have been using shampoo for years ... I use it for pinpointing after I have located the general vicinity with my GE Halogen leak detector..

Hi, Peter. It is actually on the fender side. If I shine the blacklight from the top of the engine bay, I would not see anything. If I put the blacklight right in front of the driver side front tire and shine it toward the engine, I will catch the whole side. Nothing from front nor from back seal. With regular light, I could see there are oil where there are UV active.

It seems to started right below those two allen screws whose housing has an S mark. Since I don't think oil will go down rather than up. I will attach a picture tomorrow with daylight. Hopefully it is just the oring.

Thanks.

Hi, Arthur. Thanks again for coming to the rescue. Since this time the leak was so bad that the clutch wouldn't engage no more. Shoudl I ask the shop to blow nitrogen in there to check leak as you subscripe? Also, is it ture that I will have to get a "new" compresor if the leak is found to be from teh compressor itself?

You have to have pressure to make the leak show up, so even if there is not enough to trip the compressor , there may still be enough to show on a bubble test.
Where the leak is and what is needed to fix it can not be determined till you find the leak..
Push the schrader valve in for a sec to see if there is still pressure and then try a soap test where you found dye...
If it's empty, forget it til you get some pressure back in there .
I just add a little refrigerant to get a few psi and go leak hunting...

When freon loss is sufficent to cause the clutch not to engage, how do you add freon? Do you have to jump a connection to get the compressor to run while adding freon? 1992 300SE

Tim

Took some pictures today and hope you experts could give me a better guide. There is clearly a line right around those two bolts, oil below and around it but not above it.

BTW, what is that thing coming on top of the compressor called. What o ring should I purchase to re seal this leak?

"my picture file size was too large to upload" Will take some more picture and upload them later. Sorry

Attached Thumbnails

   

Pending your pics, I would say the manifold on top (mostly, depending on the exact inclination of the compressor) or the front seal.

The manifold is held on by four allen head screws, you can probably only see two of them. The hoses are held to the manfold by a single screw, usually, on a clamp plate with the screw between the hoses. Those o-rings leak, too, when they get old.

Any AC parts supplier can get them for you, they fit a Nipondenso AC compressor, probably a 10PA15C or 10PA17C. I would guess they are the same on all Nipondense compressors.

A leak tester would be very handy here, would help locate the problem. With that much oil on there, you should be able to hear the freon hissing out if you connect a can of R134a and blow vapor into the low side (about 50 psi).

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Thanks again, Peter. The pictures are posted above. As you could see, there is nothing from the front nor back seals. And there is nothing on top of two bolts. The compreesor works with there is enough freon. Does this look to you like an o ring job rather than teh whole compressor?

On a related subject, how do you clean up that UV dye so that you can start fresh again. I used the dye a few months ago to locate a leak, and for the life of me can not clean it, so that I can see if the leak has really been fixed. Tried all sorts of chemicals, high pressure washes etc. but that stuff seems impossible to get rid of.

BTW, I don't mean getting rid of it from within the sealed AC system, but rather cleaning it once it found its way to the outside.

Phil

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'95 E300 Diesel, 264,000 Miles. [Sold it]

Definitely looks like the manifold seals to me. The two bolts have a matching pair on the other side.

To repair, you need to remove the serpentine belt (watch for a dead tensioner if it's like the M103 one!), remove the single 6 mm bolt holding the hoses on, unplug the compressor wires, and remove the four 13mm head bolts. Compressor will drop out the bottom with some wriggling about.

Remove the four bolts, replace the o-rings, and replace compressor. I'd get new hose set to manifold seals, too, they are NOT plain o-rings. Make sure you don't have grit under the bolts going back in.

Don't turn the compressor upside down or the oil will spill out.

Add a couple oz of oil when you re-charge.

That is, I think, a Nippondenso 10P15C compressor, just like mine.

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Hello Peter, I found these parts on line.

A/C Manifold Seal Kit and A/C O ring (Between connector flange and compressor. 4 per car). But I can't find any thing about a hose set. Are all these dealer only items? How do I confirm it is a Nippondenso 10P15C compressor?

Attached Thumbnails

   

Those are the two sets -- the ones with little "legs" are the ones for the hose set, the others (four, not two) go between the manifold and the compressor.

I believe the compressor number is either on the front plate (clutch) tag or on the rear above the speed sensor. Probably have to use a mirror to check this...

10P15C was used up to about 90, I think, so if you are earlier than 89, that's the one. Nice compressor so long as you don't run it dry of oil.

Yes, I do work (as a contractor) at GEAM Mt. Vernon. It is a HUGE plant by chemical plant standards, but I've seen bigger refineries. No GE plant that I know of in Evansville, though!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!