AC Leak, can you identify the part and cause?

I need help identifying the name of the part where I have a major freon leak.

The previous owner's dealership could not locate the leak, but 'ole Murphy (Law) took care of it. I had the van idling in the driveway when I heard a loud humming sound coming from the engine compartment. I began turning off stuff, radio - still there, rear ac - humming gone. So in my infinite wisdom I decided to turn the rear ac back on to see if I could locate the source. It was clearly near the accumulator and battery, but I could not find it. Then a minute later I had white smoke coming from the engine. Scared the out of me. I immediately turned off the ac (front and back) and ran to the front to see what it was. Luckily, no fire, but I had a freon stream shooting out of a brass block just to the right of the wiper motor. My guess is there was a slow leak from a bad seal and when the dealership added freon back in, wha-la, the leak became bigger... much bigger. As ac systems are my weak point, I hope someone can shed some light on this block, what may have caused the leak, and what the loud harmonic humming noise was coming from it. Here are two pics of the block. The freon was streaming from under the large nut in the center. My dealership's parts department doesn't seem to understand "Sprinterease" so they just send me diagrams and I have to pick the part that I need. Any help is greatly appreciated.

Searched for the part number here...

https://sprinter-source.com/forums/showthread.php?t=636


First check to see if that nut between the two tubes is on tight. Maybe you can tighten it, retest (turn on A/C system), and be sure to charge it soon.

I'm guessing that the system is currently discharged of freon. If you set your A/C to turn on, does the compressor clutch engage?

If the system is discharged, you can loosen the nut, and remove the part. Inspect it and maybe order the part and its related o-rings and recharge the system. I'm guessing black death has not penetrated the system since the leak is only occuring now.

After closer inspection, it also looks like the relief valve on the receiver-dryer opened as I have oil all over the top of it. Would all of this be caused by an overcharge?

Quite possible.

If I disassemble, will I need to have the system put under vacuum before I recharge?

Absolutely. I would even go as far as to leave it in a vacuum for a day or two before recharging it to check for leaks.

Probably have to replace the receiver-dryer too ?

A quick update to this issue.

I found the nut on the expansion valve practically loose enough to separate the tubing from the expansion valve. Everything was aligned and tightened. I checked the pressure in the system and found that while EXTREMELY low on refrigerant, it was not completely empty. Thanks for everyone's help!

Updated Question - Re: AC Leak, can you identify the part and cause?

Has anyone had issues with their a/c expansion valve leaking? I ordered the new o-rings for the right side of the valve from berry and installed them yesterday. Found the previous o-rings were not the correct units. New o-rings are better and do more to reduce the leak on the lower tubing. However, I still have a leak. If I move the lower tube forward or backward I can adjust the severity of the leak. I have searched both this forum and the yahoo group with no success. Any help is always appreciated.

Only reasons I can think of is if you still have the wrong size o-ring or the aluminum bar that the big tube and little tube is welded to has bowed.

sikwan said:

Only reasons I can think of is if you still have the wrong size o-ring or the aluminum bar that the big tube and little tube is welded to has bowed.

Click to expand...

Mine is not welded. It slides up and down the tubes. I suspect that warping is an issue. I have purchased a few large hose clamps that I am going to install on the ends of the metal base (around the valve) to see if I can further tighten the fittings against the expansion valve. It's not designed for it, but I am at my last resort before I start replacing the valve and tubes.

Maybe its time to bite the bullet any take it in to be fixed- the pressures in the high side are 300psig or more on a hot day, hose clamps will not hold. These lines expand and contract a great deal and there is also vibration from the engine to contend with. Froens are potentially dangerous, one drop on your eye and you are blind. Might not be a job for the do it yourselfer.

Found the problem. I cannot believe I was this blind. When I pulled the line off I caught a glimpse of what I thought was a piece of hair. It was a hairline crack right at the edge of the tube's lip. Go figure. Well at least it solves this mystery. I just wish the mechanic had found it before me.