AC Line Nut Stuck

[Parei_doll_ia]

I'm cleaning out my AC lines right now, and replacing the o-rings. It has r134 adapters on the compressor, but I don't think anyone ever cleaned the lines out, or changed to PAG oil. Some of the line nuts were stuck, so I had to take the expansion valve/small line and the condenser/lines off as a unit to get the lines off without breaking them. I've been soaking the ends of the lines in Evaporust for about 24hrs now, and I was able to get all but the nut on the small line that goes from the dryer to the expansion valve free. I tried heating it up, but it just starts to try to bend the line when I try to move it. Does anyone have any ideas to get it free? I can't find the 2 smaller lines anywhere on the internet, just the suction and discharge hoses, which mine look ok.

[eaglescout526]

You’re not by chance turning it the wrong way are ya? I had that happen the other day when I was pulling some parts. 

[Parei_doll_ia]

1 hour ago, eaglescout526 said:

You’re not by chance turning it the wrong way are ya? I had that happen the other day when I was pulling some parts. 

Yeah, I already got it out of the expansion valve, the nut was just rusted to the line. I spent many nights thinking about what way I was turning a fastener that I couldn't see when I worked on F18s.

 

I guess 36 hours was the magic number in the Evaporust, I finally got it loose. Now it gets dunked again to get the rest of the rust off.

[eaglescout526]

Damn. That thing is rough. 

[cruiser54]

Try using Freeze-Off in the future. Amazing stuff. 

[AZJeff]

Was there any reason you didn't lay into it with a propane torch?  If the expansion valve was aready off the vehicle, the amount of refrigerant was pretty much zero, so heat would not generate noxious gases, but it sure would loosen that rust.

[Parei_doll_ia]

16 hours ago, AZJeff said:

Was there any reason you didn't lay into it with a propane torch?  If the expansion valve was aready off the vehicle, the amount of refrigerant was pretty much zero, so heat would not generate noxious gases, but it sure would loosen that rust.

I did, a little bit. I don't usually have problems getting line nuts loose, this one was just particularly stuck and didn't want to break something that I would have to get custom made for a replacement. 

[Parei_doll_ia]

Also, are these check valves on the drier necessary? It seems weird to put 2 of them in series. Some XJ posts I found said they just gutted them.

And the 2nd one is backwards from how I took it out in this picture. It seems like they're opposing each other and don't allow flow?

[AZJeff]

I think that "check valve" is an overpressure safety valve.   I am not familiar with all the fittings on the older MJ's, but that is what they looked like on my old Ford F150.   I am certain that others can confirm if that is what this part is on your MJ.

[Parei_doll_ia]

On 6/17/2022 at 4:52 PM, AZJeff said:

I think that "check valve" is an overpressure safety valve.   I am not familiar with all the fittings on the older MJ's, but that is what they looked like on my old Ford F150.   I am certain that others can confirm if that is what this part is on your MJ.

From some more internet searching, I found the same valve on an old RV forum. It's a service valve, probably used during manufacturing. It doesn't really serve any purpose now, but I couldn't figure out a way to gut it without it leaking. I replaced the o rings and it seems to work fine. I could even remove the 3/4 fitting without losing much vacuum. 

 

It held vacuum all night, so I just charged it with 24 ounces of r134. The vent was showing 42 degrees, hopefully this lasts.