HVAC copper tube fitting/weld correction prevention

Old 09-09-16, 07:15 PM
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Question HVAC copper tube fitting/weld correction prevention

Hi, i noticed the outgoing copper refrigerant line has few welds (appears to be combined with aluminum) that are showing bluish/black residue, getting worse year after year sitting in the humid attic. Is there any way to prevent this from getting worse? Like add a bearing grease, lithium grease, wax, heat shrink, etc? Is it necessary/any harm adding a moisture barrier? What's safe?

My fear is that these points will leak... there appears to be a tiny/really slow leak in our 10 yr old unit.

Thanks in advance,

Last edited by Edward Law; 09-09-16 at 07:42 PM.
Old 09-09-16, 09:51 PM
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The "welded" fittings are actually brazed using Sil-Fos. A silver phosphate product. Pretty much impervious to the weather. The fittings may blacken but they won't corrode.

You can wire brush them clean.

Tiny leaks are usually the fault of test valves/ports that aren't sealing fully.
Followed by a leaky evaporator coil.

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