Automotive Air Conditioning Information Forum (Archives)

mtwask01 on Tue January 12, 2016 7:28 PM

Year: 1969
Make: AMC
Model: Javelin
Engine Size: 390
Refrigerant Type: R-12
Ambient Temp: N/A
Pressure Low: N/A
Pressure High: N/A
Country of Origin: United States

I have a question regarding the difference between these two connection types. I know that older cars (like this one) almost exclusively used flare fittings. I also know that older car a/c systems were notorious for leaks (leaky shaft seals, non-barrier hoses, etc.) and that it was not uncommon those days to have to top off the system every season or two. New cars on the other hand almost exclusively use o-ring fittings (can't think of any that don't but I'm sure they're out there). Likewise, newer cars have a much better ability to hold their refrigerant charge, lasting several years and beyond. There had to be a reason for OEMs to switch from flare to O-rings. Was this because O-rings seal better? My ultimate question is if flare fittings part of that equation of leaky a/c systems of the past, and would flare fittings hold an R-12 charge for a decent amount of time (5+ years, the longer the better). I plan to upgrade to beadlock fittings and barrier hose as well as a new compressor and lubricating all seals with nylog red. Should I go ahead and change the fittings to the modern o-ring type or will the flare fittings be ok? Rebuilding this a/c system is something I prefer to do right the first time and lasting a long time.


Thanks guys, this is a great forum with lots of good information.
Matt

mk378 on Thu January 14, 2016 7:55 PM

Flare fittings can be reliable and air-tight (actually tighter than an o-ring, since it's metal on metal) but there is a fairly narrow range of acceptable torque on the nut. If you over-tighten and distort the beveled surface on the male fitting, it will never seal again. O-rings are a lot more forgiving.

You could go all the way modern with a parallel flow condenser and R-134a, being a lot less expensive to replace if it leaks out.

mtwask01 on Fri January 15, 2016 1:56 PM

Thanks for the reply mk378. That's good information to know. Do you have a good rule of thumb to know when it is tight enough? I am guessing that you just snug up the flare fittings and don't go overboard. I will put some nylog on the flare seating surfaces to help with sealing as well.

mtwask01 on Fri January 15, 2016 1:56 PM

Edit: sorry duplicate post

Edited: Fri January 15, 2016 at 1:57 PM by mtwask01

Dougflas on Fri January 15, 2016 4:02 PM

They also have copper seats you can put in a flare fitting that is slightly distorted. I also have R12 if needed.

mtwask01 on Fri January 15, 2016 8:14 PM

Thanks for the reply Dougflas. I'm not an expert, but just from looking at this flare, I think it is in good enough shape to reuse. This is the only flare I plan on reusing. I have some R-12 to recharge the system, but I appreciate the offer.


Because these fittings are steel, I am considering painting them to prevent corrosion. I'd like to use a paint to give it that clean bare steel silver color, but I'm not sure of what type of paint to use. Has anyone here painted a/c hoses.?

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Edit: pictures don't seem to be working here's a direct link:

A/C Flare

Edited: Fri January 15, 2016 at 8:18 PM by mtwask01

Dougflas on Sat January 16, 2016 2:27 AM

I would NOT paint the flare surface. USe some refrigeration oil (525) or Nylog on the flare surfaces.

Cussboy on Sat January 16, 2016 8:50 AM

Quote
Originally posted by: Dougflas
I would NOT paint the flare surface. USe some refrigeration oil (525) or Nylog on the flare surfaces.


Agree.

mtwask01 on Sat January 16, 2016 11:28 AM

Quote
Originally posted by: Dougflas
I would NOT paint the flare surface. USe some refrigeration oil (525) or Nylog on the flare surfaces.

Ok, I wasn't planning on painting the flare surfaces. Those will get some nylog red on them. Would painting everything besides the flare surfaces be ok?