Question on adding gas to BD35 compressor

[Uncle Bob]

Originally Posted by Warby12

Hi Richard, thanks again. I have it running now with the thermostat bypassed at three amps and no problems so far. I will keep watching, it's not very hot now, also the fans are on a relay so can't draw too much.

But! I may have to put that to one side because I have noticed the line is still leaking somewhere, as can be seen in this photo I have just taken, there is a drip of (I guess) oil on the capillary tube.

Where can that be coming from? Above that tube is the entry point for the capillary into the low pressure side. If so can that be fixed or do I need a new evaporator, do you think?

Quick question/observation, could this drip by any chance be condensation? Have you done a check to see if it is merely water or does it have an oily feel?

[Warby12]

Got all excited for a moment there Uncle Bob! Went and checked straight away.


No it's a clear oily substance

[Coolerking]

Its most likely refrigerant oil.
The cap tube enters where you see it above the fitting in your pic. It then travels inside the suction line to the evap plate, if you look close at the plate you can see the small crimp they do on the cap tube as it exits beyond the end of the larger low side line.
Inflate the system with 100lbs dry nitrogen, and get the soapy bubbles going, you can then make the call as to weather or not it can be repaired.

[Warby12]

Hi Coolerking, thanks for the information and advice. I can't access Nitrogen here on anchor.

I guess the best pressure I can get is from a running system, I can add resistors in the thermostat line to get it running at 3500 RPM = more pressure = more bubbles?

If I can find it I can decide what's next, attempt a repair or replace with a new component (Ouch)

Thanks again.

[Coolerking]

You need to make sure the entire circuit is in a positive pressure state, you might have better luck just turning it off and letting it equalize.
Keep in mind that if you have a leak, then the lo side may be in a partial vacuum, in which case you dont want to put anything on it that could get pulled into the tubing.

No soapy bubbles on it until you are sure both sides are positive pressure.

[Richard Kollmann]

Warby 12, you could replace evaporator assembly for under $500 or try to stop the external leak with JB Weld.
First clean area of both tubes at least one inch away from joint with a good solvent like MEK then apply JB Weld and wait several hours before putting refrigerant back in system.

[Warby12]

Thank you Coolerking and Richard!

Coolerking, that is excellent advice and makes a lot of sense. I will try one more time to find the leak after it has rested.

Richard, thanks again. I am still appreciating your comment that the compressor cannot overpressure and turn off from a moisture/capillary blockage. I was on the wrong track there

If I cannot find the leak, I will try and seal it, then I can evacuate and refill and that should buy me the summer at least.

Again, your help is incredibly appreciated.

[Warby12]

I've found the leak!

I know it's been awhile but the fridge has been working just enough to avoid replacement but wont survive another summer. Time to either fix it or replace it (ouch!) Since it is worth nothing now, fixing it is completely worth a shot.

To find the leak, (soap didn't work) I ended up wrapping paper towel around all of the accessible piping, held it in place with foil, charged the gas, let it get good and hot without condensor fans (kept one on the control module) and the tell-tail oil stain appeared

Does anyone think it's repairable? It's where the capillary tube enters the suction line, on its way to the evaporator. As suggested, I could epoxy the area, which I am happy to do but is it feasible to resolder this? I only have a butane torch.

I am a competent welder so understand heating metal etc but I'm worried that with all of the oil residue, and the risk of flooding and maybe blocking the suction line with solder, I'll make it worse.

What do you think?

[Pete7]

Don't think you have much to loose. Shame its right on a junction or I would suggest an epoxy cloth bandage. May as well have a go soldiering it.

[Warby12]

Hi Pete7, thanks

I'm wondering if an extreme clean and good flux will prepare the surface well enough? No idea. But like I said, I'm worried I'll flood the suction tube with solder.

Any recommendations on a suitable solder for this with a butane torch?
All good fun on a faithful but old-ish system. I'd be really pleased if I can keep it going.

[Coolerking]

Be careful of the copper to aluminum joint.
Any Nickel bearing solder will work, we use Bridgit (Google it).

The prep will take 20 minutes, the soldering will take 10 seconds.
Good luck!

[Warby12]

Thanks Coolerking, I'll try and grab some suitable solder and flux for the butane. I need to clear away the insulation behind too and I guess wrap some wet rags. Should be an instructive experience

Another question, if I dare? I'm thinking I should go all in and replace the filter dryer but I'm not sure of the sizing of filter dryers. I can see on the internet. the O.D. of the high pressure tube on the Danfoss BD35 seems to be 3/16th (5mm) So what size filter dryer? Is 1/4" right?

Thanks for any help