He has been a little unclear at times, but I think this Paul Krugman post, which is about his view that Hayek misunderstood the sources of the Depression, summarizes his (Krugman's) position nicely:
Just to be clear, I don’t think the Smoot-Hawley tariff was a good thing — it was a really bad thing. Nasty protectionism! Bad Smoot-Hawley! Bad! Bad! Bad!
But did Smoot-Hawley and other trade restrictions cause the Depression? No.
Bear in mind that what protectionism does, according to textbook economics, is to cause a misallocation of resources, reducing the economy’s efficiency. It does not cause mass unemployment of resources — which is what the Depression was about.
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But going back to Hayek: attributing the failure to recover to trade restrictions was, in a way, characteristic. Hayek, like his modern followers, never could get his mind wrapped around the fact that the key problem in depressions, and the key observation his theory needed to explain, wasn’t misallocation of labor and other resources — it was mass unemployment. It’s not surprising to see that in the depths of depression he was focused on removing what was, in the end, a minor source of allocative inefficiency.
So in his view, protectionism is bad, but is just a "minor source of allocative inefficiency," and there are more important economic issues to be worrying about right now. Of course, as noted many times on this blog, he spends a lot of time worrying about Chinese currency manipulation, which he considers to be a form of protectionism ...
