Help my underbelly condensor leaks !!

rfuerst911sc · 02-19-2005, 10:13 AM

Well I thought I was done with my AC upgrade,to bring you up to speed I bought a used underbelly condensor off Ebay along with another condensor for the rear fender and removed the rear engine condensor,anyway I finished the install and pulled a vacuum today,it went down to negative 28 inches or so and I let the pump run for an hour,however when I shut the pump off the vacuum quickly returned to 0...........crap!!! Well while I was looking for leaks it became apparent the underbelly condensor was the culprit,my 1st clue was the large puddle of refrigerant oil on the ground. It appears that one of the solder joints at an elbow is leaking,in hindsight I should have had the unit pressure tested.How can I fix this?It looks like it's copper like plumbing copper can I just clean the area,add flux and heat and solder??I am very frustrated at the moment,any ideas would be appreciated.

Hugh R · 02-19-2005, 10:16 AM

I've solder a/c connections before. You may want to braze it though, its a stronger fix.

scottb · 12:01 PM

If it's truly a solder joint, then it is easily fixed. Do a search on the 'net on sweating solder joints on copper tubing. Here's one article.

Basically the idea is that you heat the fitting and the tube inserted into it with a propane torch such that the solder melts and, using a capillary effect, it flows into the space between the tube and the elbow. Don't try to solder around the joint....get the solder to flow into it. If done correctly, solder will hold up just fine for an a/c system.

Alternatively, take it to a local a/c shop and have them do it, and then pressure test it.

Good luck.

rfuerst911sc · 02-19-2005, 12:30 PM

I have calmed down a little and I went and purchased some paste flux and plumbing solder.I have a oxy/acetylene welding setup that I'll turn the pressure way down so I don't burn thru.I will attempt the repair tomorrow.Thanks guys.

scottb · 02-19-2005, 01:03 PM

Good luck. Let us know how it turns out.

stormcrow · stormcrow's Garage

You might want to be careful about "soldering that joint" It probably is a silver soldered joint, not a lead/solder joint. If you have a oxy/acet rig you can purchase silver solder from one of the air conditioning supply houses.

Silver has a much higher joint strength than lead/solder. The acid that you use for the lead joint will eventually corrode and you will have to deal with the leak again. Do it right the first time and you won't have a problem.

Steve

"A Porsche does more then just go fast in a straight line"

AFJuvat · 02-19-2005, 06:14 PM

Make sure you disconnect a hose or open one of the schrader valves on the system before you start heating up the system with a torch - overpressure = BOOM

AFJuvat

rfuerst911sc · 02-20-2005, 03:04 AM

I have flux coated brazing rod should I use that instead? I have to do this repair under the car meaning upside down,now I'm getting nervous again.Any additional advice? Thanks.

3.2 CAB · 02-20-2005, 05:17 AM

I would remove it in order to get all the way around it, if it is at a joint. If it is just a pinhole on the underside, you might be ok to attempt the repair with it still installed. Check to see what the other joints are done with, lead, or the silver solder and use the same type. I would think that they are the silver solder type, due to the pressures and temps involved.

rfuerst911sc · 02-20-2005, 05:21 AM

How can I tell visually if they were done with conventional solder or silver solder?

scottb · 02-20-2005, 08:29 AM

Quote:

Originally posted by rfuerst911sc
I have flux coated brazing rod should I use that instead? I have to do this repair under the car meaning upside down,now I'm getting nervous again.Any additional advice? Thanks.

You should drop the condenser down from the car. I'd go the silver solder route.

vlocci · 02-20-2005, 08:44 AM

Easy rfuerst911sc,

take a moment to think a bit. It sounds like you at least filled the system with some refrigerant (leaking refrigerant oil on the ground?)

If so, you essentially have coated a good portion of the interior of the underbelly condenser with refrigerant oil. With enough heat, this stuff is flamable, so before going ahead and silversoldering away take the time to at least flush the underbelly condenser. Before bursting into flame it still smokes like mad which is not good for things like the exp valve and dryer.

Additionally, if the insider of the condenser is coated with refrig. oil your going to likely contaiminate the brazed joint and it will become difficult or impossible to trulely seal things up. Furstration leads to a burned through joint and now your in trouble and are forced to take everything apart anyway.

If it was me, take the time to pull the condenser, flush it with something like laquer thinner and LET THE THINNER EVAPORATE before trying to silver solder things back in place. At least this way you can work in a comfortable position to get things done right the first time. Weilding an oxy/acetylene torch upsidedown while silversoldering a contaminated joint on my back inches from the pan is not my idea of a good time.

You can pick up a few silver soldering rods from any welding distributer, and at the same time can but the appropriate tip for your oxy rig. Probably a 20 dollar investment.

Give a hollar if you need any tips.

Vin

scottb · 02-20-2005, 09:12 AM

Rfuerst: Vin's advice is solid. I know you've been working on this a long time, and you're anxious to see it work, but take the time here to be safe and do it right. Remove the condenser and flush it first with something like lacquer thinner or denatured alcohol. Then blow compressed air through it to get out as much liquid as possible. Then let it dry thoroughly. At that point, you'll be good to go for the repair.

rfuerst911sc · 02-20-2005, 10:54 AM

Excellent advice guys,I am getting anxious to get this system up and running but it has to be done right so I will remove the condensor,flush it and I'll probably take it to someone to have it done or maybe I'll try it myself.I planned this for months,carefully put together all the pieces,had each hose made one at a time and now this damn thing leaks!!!! The joy of DIY..........thanks guys.

scottb · 11:48 AM

Quote:

Originally posted by rfuerst911sc
I will remove the condensor,flush it and I'll probably take it to someone to have it done or maybe I'll try it myself.

You're right...this stuff is all part of the "joy" of DIY. You can probably do the repair yourself without too much difficulty (especially if you have the condenser out of the car), but at this point it might make sense to have a pro do the repair who can also pressure test it once the repair is done. IIRC this is a used condenser you got on eBay, and a pressure test might be a good idea before you re-mount the unit, re-plumb it, and then try to vacuum down the system. The repair and pressure test should only cost you a few bucks, and it will give you lots of peace of mind.

You're almost done, so hang in there!