Hi,

I believe my wife's 87 16v 190e has a leak from the compressor. I charged it last summer with R12 and dye. Worked marginally through the summer with pressures in spec but vent temps only in the high 50's to low 60's.

This spring it blows cold on the first first start the day and then as coolant temps rise and its driven some distance, the AC starts to drop out at stop lights and resumes at speed. Eventually getting mostly hot air. I figure a loss of freon.

I got out the black light today and noticed dye on the lower rear of the compressor. No trail of dye from the front. Is there a rear seal on the compressor? Replace the whole compressor?

Thoughts? A good source for AC compressors? Our host doesn't stock one for my model.

Thanks.

Tinker

Is there a LOT of dye at the rear of the compressor?

When you put in dye, especially in an R12 system where the refrigerant is expensive. You need to use your black light while the system is charged and working well rather than waiting until it is empty. That way you can look at the condensation water to see if it has dye in it. If there is then it is the evaporator. Once it is empty the only way to confirm the evaporator is to tear everything apart to examine the evaporator.

If there is only a tiny trace amount of dye at the point you describe, it may not be your main leak.

Best of luck,

Larry,

Thanks for responding.

When I initially installed the dye, I went over the whole system with the black light and found no leaks.

I don't think I have read about issues with the evaporators in the 201 chassis?

The dye on the back of the compressor is a good amount, easily noticeable with the black light. About the size of a cue ball or larger. I would consider it ALOT.

Thoughts?

Tinker

I'm not familiar with the compressor on your model. Does the leak look like it is coming from the seam of the rear plate? If so, you might be able to tighten the bolts holding that plate.

If it seems that the bolts are taking up the plate, clean the existing dye so you can later tell if you fixed the leak.

Best of luck,

Tinker:

If you show a leak on the rear of the compressor, it's likely your speed sensor (attached to rear) or one of your case section O-rings is leaking. (red lines in pic below) It appears you have a Nippondenso 10P15C compressor on your 190E.

I recently rebuilt my Nippondenso compressor and it was surprisingly easy with the help of this article. Tightening down the 5 section bolts as Larry mentioned might do the trick too.

My leak was coming from the middle section O-ring. The only 'special' tools you'll need are a pair of snap ring pliers (for the circlips) and a strap wrench or large channel locks to hold the clutch while removing the front bolt. Autozone also lends out a compressor clutch holding tool.

You can purchase the gasket kit from www.acsource.com

Good Luck

__________________
-Paul-
'01 E430, Sport 72,000 mi
'98 C280, 126,500 mi

Thanks for the info guys. Great links Paul!

Guess I am going to have to crawl under and take a closer look.

The referenced article for the 911 does not mention the speed sensor in the rear. I assume there is a seal for that also? From the picture you posted it looks like there is circlip holding the rear sensor in place.

Paul, did you completely rebuild yours or just took it down to the leaking center seal?

Once/if I get it apart, how can I tell if its worth rebuilding? Any damage to the piston/bore areas should I assume its junk? Other than the seals, what wears out/fails?

Thanks again.

Tinker

Yes, the speed sensor is held in by a circlip and does have an O-ring behind it, as shown below.

I believe my gasket set came with a new speed sensor O-ring but I'm not positive. Most likely available at your local dealership. Since mine wasn't leaking, I left well enough alone. Same goes for the shaft seal. I had planned on replacing it but since it wasn't leaking, and I didn't have the proper tools to get the old seal out, I left it alone.

It looks as though you can replace the speed sensor O-ring from the rear without having to open up the entire compressor. I would make absoutely sure though where exactly the leak is coming from.

The low pressure switch pretty much protects your compressor, unless it has experienced the infamous "black death". You'll know when you open it up (even just the rear sensor) if it's worth the effort or not. Look for metal particles, gunk etc.... Most likely though you'll find clean oil inside making it very rebuildable.

Mine looked like new inside with 238,000 miles on it. I was pretty amazed.

Good Luck

__________________
-Paul-
'01 E430, Sport 72,000 mi
'98 C280, 126,500 mi

Paul, Larry,

I crawled under it tonight and it is definitely leaking from the rear speed sensor. No way to get at it without removing the whole compressor from the car, so it will have to come out. Should I just fix what's broken (the o ring) and leave the rest alone based on the inspection? Nothing else should be replaced while I have it out? Car has 150k on it. I plan on replacing the dryer/receiver since the sytem will be apart

Paul, where are you obtaining these great photos from?

Thanks again.

Tinker

If the compressor was working well before it lost charge and is not noisy, I would seal the leak, add a few ounces of oil and recharge.

Good luck,

Larry: The r-12 system in my car has a slow leak and when i recharge the system this summer, i would like to include dye to see if i can find the leak. I have not found a source to purchase dye and i do not know how much dye to use. I have seen 134 with dye included but not r-12. Any suggestions

420,

AC Source, as posted by Paul sells it:

http://www.acsource.com/index.asp?PageAction=VIEWCATS&Category=263

I bought mine from the Tool Warehouse.

http://www.thetoolwarehouse.net/shop/TP-TP1121.html

Tinker

This is a great thread. I have learned a lot, thank you. If I may jump in with a quick question:

If a compressor won't turn and when the clutch is made to engage and it stalls out the engine (compressor bad) but does that also mean it is "the balck death"? Therefore the compressor is toast and the whole system definitely needs to be cleaned as Larry and others have described?

Haasman

__________________
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)

Tinker: thanks for the info, great site.

haasman,

You won't know for sure until you disconnect the compressor lines and look for debris, but I fully expect that this compressor is toast. When replacing you will have to flush EVERYTHING until you're absolutely sick of flushing.

Good luck,