Is Blackish copper tube can be useable?

10 November 2022 0 6K Report

The copper condenser is stored in dry air conditioning. After 7 months the copper condenser turns into blackish color on the tube surface.

2. Under the foil tape the tube could not /be observed blackish color.

My question is can we use this blackish color?

3. If we rub with hand , the blackish color will go away.

Below given I some pictures of blackish color tubes.

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