AC Evaporator O rings

Ok so I am back again because I cant seem to find the answer to my question anywhere. Does anybody know if the top and bottom O ring that sits on the evaporator is suppose to be on the outer part of the hole or the inner. Is there even suppose to be O rings on these spots? Ive bought basically every o ring pack you could buy and not a single o ring fit properly on that bottom connection. Is it ok to stretch the bottom o ring out to fit and then hold it down with some silicone sealant? I went all summer with a huge leak at the firewall on 3 different evaporators.

The O rings go on the pipe that goes into that fitting, they do not sit in the recess as u have it shown here, and get O rings for an AC system not oil or water ones.

Ive got the green O rings which I purchased off of rock auto for this car. This entire confusion came when the dealer told me the bottom O ring that goes on the evaporator broke and was leaking dye everywhere. So you are saying that there is not suppose to be an O ring on the top or bottom connection? Only on the ac lines that go into those holes?

Correct, if u look at the male fitting u will see a boss that goes into the recess that u have put the O rings into. The O ring goes on the pipe up against that boss, there is a groove in the pipe that the O ring fits into.

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Ok so this must have been my problem the entire time. I kept putting O rings on the evaporator and it was causing the ac lines not to seal properly because they were getting in the way.

Right, but your AC man should have told u that LOL, so lets hope u are now sorted.

Well when I first brought it to the dealer they told me the O ring on the evaporator is cracked and leaking dye everywhere. He also said that the hose going into that bottom connection was leaking and recommended replacing both the hose and evaporator. Then I brought it somewhere else and they said the same thing. Both are leaking. So this entire time I thought there needed to be O rings on the evaporator plus the hoses. I kept putting different O rings on the evaporator, Bringing it in to see if it holds pressure but nothing worked. There was just a non stop giant leak at the firewall. I tried 3 different evaporators, 2 different hoses. And this whole time it turns out that me putting O rings on that evaporator was the problem all along I guess. When it gets warm out ill have to put my original evaporator back in and test it.

So an update on this. Put a good evaporator and low side hose on my car. Put a new Green AC O ring on the low side hose (I ordered an oem one from mitsubishi but it was the wrong size that I ordered) It still leaks on the low side hose connection and I cant figure out why. How is it possible its leaking from the same spot on 2 different evaporators/hoses? Has anyone ever removed these hoses and hooked them back up and the freon didnt leak out from that spot? I cant figure out why it keeps leaking from there.

O-rings could not be the issue, these lines are very fragile made out of soft aluminum, so a good possibility you have a hairline crack somewhere, which you will need to get yourself a endoscope to get a closer look, if you are not able to get in very tight areas. Clean all the areas where you think it is leaking with parts cleaner, let dry for a while then turn your system on and observe. The refrigerant is colored, so you should not have any issues identifying the area of the leak.

The spot of leak is for sure low side hose connection to evaporator. I first replaced my low side hose but kept my original evaporator. It still leaked from same spot. Then I replaced my evaporator and it still leaked from same spot. Then just the other day I removed the o ring from the low side hose and put a green o ring on and still leaked from same spot.

With any leaks the idea is too visually see it happining with special visual aid equipments such as an endoscope so go get yourself one you wont regret it a must have tool for any mechanic

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You mentioned flushing your ac system. If I want to put my old hose back on, how would I go about flushing it out? I ask because its been sitting in my shed collecting dust. Do I simply just run water through it?

Google A/C flush solvent and use that

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An update on this. System finally seals and no more leak at the firewall low side hose connection. Both the generic green O rings as well as the black OEM O rings did not seal at that connection. A thicker O ring on that low side hose connection did seal the system.

That is good news, by looking at the pic the o-ring looked way to small as far as thickness is concerned, as I mentioned earlier. Now you know what the thickness should be and pass this info on to others that may have the same issue.

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