Plumbing question

[Curmudgeon]

I have a double vanity in which the sink on the left drains very slowly when water is first run. If I let the water drain out then run the water again immediately the sink drains normally. The popup, tailpiece and trap are all clear and operate normally; the sink on the right does not exhibit this problem. This is unlikely to be a blockage since the problem has been present since the house was first built; also, if there were a blockage I don't think it would drain slowly one minute and then freely when the water is run a second time.

Any ideas?

[EXT]

Not without knowing how they are plumbed. Do they connect together under the sink in the cabinet or do they enter the wall separately. Inside the wall they are often connected to the vertical stack with a "cross" fitting, something could be blocking one side and not the other, try snaking the line out.

[Joe]

You have a blockage, probably hair, but you just haven't found it yet. Keep looking, it's there.

Joe