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? about leak detection dye

hardbody on Mon April 04, 2011 4:52 PM User is offline

Year: 1990
Make: Nissan
Model: Sentra
Engine Size: 1.6
Refrigerant Type: R134
Country of Origin: United States

Hello, 90 Nissan Sentra, when I first bought this car about 5 years ago I took it to a shop to check the AC as it wasn't working. that shop injected that green dye into the system to find a leak. I don't know how much dye they put in compared to how much should have been used. They found a leak at the low pressure switch and couldn't get a replacement switch so I took it to the guy that I currently use, he said they used way too much dye, I had him replace the compressor (reman unit I provided) and we also replaced the expansion valve and the drier. AC worked great blowing about 30 degrees for about 11 months when the compressor failed. He had told me the rebuilt compressors were garbage and only last about a year that I was better off getting a used one from a junkyard. Anyway auto parts store replaced the compressor under warranty and I also bought a new expansion valve and drier. Had my tech replace the compressor,expansion valve and drier again. Each time system was worked on that green dye would still come out. Well 2nd compressor took a crap again, auto parts won't warranty it so yesterday I took the compressor out of the car and took it apart. I found the screws that attach the magnet under the pulley to the compressor housing had all sheared off allowing the magnet to rotate with the pulley breaking the magnet wire and gouging the hell out of the front of the compressor, causing the metal to metal noise I was hearing!

I read yesterday (on another site) about flushing an AC system and the article I read was saying the drier will catch most debris and it wasn't necessary to flush the evaporator because of this. My tech checked the evaporator last time he worked on it and there was no dye in it ( or at least none came out), I also had a metal line and a rubber line repaired as they both had leaks and no dye was in them.

My question is, where is this green dye hiding in the system so that it still comes out after having all these parts replaced twice? Does the dye effect performance at all? I just ordered another rebuilt compressor and will be ordering a new expansion valve and drier soon so that everything will be new when I have my tech install the new compressor. Should I have him flush the system before installing the new parts? I also read it is best sometimes to take the system apart and flush each part separately which I don't have any problems doing. I try to help my tech if I can to make his job easier.

Thanks for any info you can provide appreciate it!

JACK ADAMS on Mon April 04, 2011 6:37 PM User is offline

Here is a link for Flushing!. This is the best thing to do if you want to do it the correct way!

mk378 on Mon April 04, 2011 6:46 PM User is offline

Yeah after these multiple replacements, flushing out all the oil and dye so you can start over is the way to go. If you've had a compressor blow up / seize it might be best to just replace the condenser rather than try to flush it. Dye in the proper amount (1/4 ounce) won't affect performance. The dye rides with the oil, that is why it is so hard to get rid of.

hardbody on Mon April 04, 2011 8:23 PM User is offline

Thanks, Any idea what would cause the magnet assembly to get loose and shear off the screws?

mk378 on Tue April 05, 2011 1:42 AM User is offline

Most likely scenario is the bearing failed, pulley begins to wobble, until it catches on the magnet. They are designed so there is not much clearance at all between the magnet and pulley.

HECAT on Tue April 05, 2011 9:54 AM User is offline

21 year old car, system inoperative and history unknown. Charged with dye found leak. Suspect too much dye, changed 2 compressors, 2 expansion valves, and 2 dryers. Now an apparent shaft bearing failure. The green dye stays with the oil when the refrigerant is recovered (or leaks out). The dye does no harm (unless too much is used) but the quantity and quality of the oil is critical to compressor life. You cannot blow the oil out of a component with air, it is smeared all over the internal surface area; and these components are designed for maximum surface area. Yes you should flush this system clean and dry before you do another rebuild. If you cannot properly and confidently flush said components then replace them. Please read the PDF file below.


HECAT: You support the Forum when you consider for your a/c parts.


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