I have a '03 E150 with 5.4L & dual AC, Has just under 50K miles.

The AC is leaking freon from joint where compressor line connects to the condenser, tried tightening the joint, still leaked. Tried making it real tight - still leaked. Pulled it apart & checked for cracks, found none. Polished tube & fitting where O-ring seals. Have replaced the O-ring 3 or 4 times, tried Ford parts, tried aftermarket parts, even tried oversize O-rings. Tried a nylon washer behind the O-ring to force it further into the taper on the compressor line. Tried AC oil to lube the O-rings, & tried spark plug dielectric silicone. Best I can do is make it hold vacuum, but not operating pressure. I am using the UV dye to confirm the leak is at the joint.

I suspect I damaged the joint by tightening it past the specification. Any one have any tricks to make this seal? Anyone tried Nylog?

Nylog video Nylog, HVAC Gasket and Thread Sealant.mp4 - YouTube

 

Vacuum is 30 inHg, operating pressure is 300 psi. No comparison.

I never had luck with adhesives doing a job that mechanical fastening can't. Only the other way-around works.

Never tried Nylog, but have tried other "heavy duty" sealants. I no longer waste my time with these.

If anything, I would only try products that hydraulic shops (the one that service construction / roadwork equipment) carry, which are designed for operating environments of 3000-4000 psi.

 

Chances are you've either deformed the connection fittings or cracked the condenser line itself. As Henry says sealants and such aren't intended to replace or repair a joint that's not mechanically sound.

Steps already taken should have stopped the leak---might be time to think about replacing the damaged part or parts. There is also an A/C Forum here where someone with more specific experience could direct you: Cooling, Heating, Ventilation & A/C - Ford Truck Enthusiasts Forums

HTH and best of luck----not the season for non-working A/C!

 

Henry10s & JWA,

Thanks for the recommendations. Your analytical perspectives helped. I agree the "glop" isn't the desired fix, I was just frustrated & at my wits end after battling the problem all weekend. I especially appreciate the pointer to the AC forum. I haven't had time to do much research there, but if there's a technique I have missed, it will probably be in there somewhere!

I did order the sealant, and I'll maybe give it a try next week if I don't have success tomorrow. I thought about the problem a little more and how the joint functions. It does the sealing between the O-ring's ID and OD. That's why my ground down O-ring didn't work- the OD surface was way too rough. I now think that Yes, I either deformed the fitting, or I scratched the sealing surface with my calipers while measuring for the O-Ring size. I'll try polishing the surfaces again, this time with the Dremel mototool with a cotton bit & super fine polishing compound. I'll also try to determine the joint's geometry by using something like modeling clay in the joint to see if I can detect anything non symmetrical. Of course, I'll have to be super careful to make sure to neither the polishing compound or or the clay get into the system.

 

I tried cleaning & polishing the fittings, and that helped a little, but it still leaked. I got the Nylog sealant and a new o-ring and tried again, and it's the slowest leak yet, but I can still the UV dye bubbling from the back side of the joint when it's under pressure.

I am fresh out of ideas, so I'll resort to replacing the condenser.

When I over-tightened the fittings, I probably cracked the tubes where the sealing rings are formed into the tubes. That's a sharp angle, so it's a stress concentration point, and that metal is pretty soft.

 

I replaced the condenser coil and that fixed the leak. It was a rather expensive lesson, as I probably spent about $400 before solving the problem.

It turns out that the condenser coil has TWO cracks at the fitting. One which I caused by over-tightening the joint, and another that was probably the source of the initial leak. The latter is either a vibration crack or the part was perhaps miss-formed during manufacture.

The attached photo shows the two cracks. Does anyone know of a kit that replaces the fitting end of the condenser? For a $ 30-40 kit, I'll keep the old condenser as a spare.

As an aside, When I have to "top-off" the Freon in my AC systems, I'll be sure to use the Freon with the UV dye. It works great and really makes finding leaks easier.