yellow powder

I recently had a problem with a Liebert close control air conditioning unit. I diagnosed a blocked drier, recovered the refrigerant and removed the offending article. The inside of the liquid line and drier inlet was coated with a fine light yellow powder. I have recommissioned the system and it is now working aok.
The system is five years old, running on R407c. It has done done much work until quite recently. Is this powder some kind of copper oxide? Was this system not evacuated properly when it was new?
Would appreciate any ideas!!!

Copper oxide would be black. It ends up looking like soot from a fire.

I'm not sure what the yellow powder would be. For some reason this rings a bell in the old memory, but for the life of me I can't remember where it comes from, or what causes it.

Perhaps one of our other members (Johnny Rod) can shed some light on this.

Hi

If you search chillyhamster posts on 210605 you,ll find

an explanation to your question.

Cheers Bernard:)

Interesting Bernard, but I don't think it was a broken down drier, all the powder was in the liquid line before the drier, none after, and it had partially blocked the drier. The drier is a 5/8 flare drier 8cu in solid core.

It probably is copper debris of the original installer

Not convinced, it was a very light yellow powder.

It does sound like drier material, though not sure why it is upstream of the drier, unless as you recovered the charge you sucked back through the drier and it shed bits. Only thing I can suggest is you scrape together enough for analysis, confirm its identity. I can do this if you like, other analysis providers are available!

Maybe some solid lubricant used for expanding the copper pipes in the coil?
Since Liebert most of the time buys coils in NE Italy, by looking at the label on the coil I may contact the supplier of Liebert.

Just had a wild thought on this subject.

Is the compressor/condenser remote from the indoor unit? Would the suction line have been insulated during the install period?

Now for the big question... Is there any trace of similar powder inside of the insulation on the suction line? Sometimes the insulation manufacturer applies a fine power to add in slipping the insulation onto the tubing.

If the insulation was slipped onto the suction line and the suction line tubing was open during this, a lot of this powder could have ended up in the system.

I might be reading between the lines too much, but I thought I would throw this out for comments.;)