HVAC/R copper is typically OD. Water copper is ID. So.... your "too large"
fittings are probably water copper, and the tubing is refrigeration copper.

At least, that's my memory of how it works.

--

Christopher A. Young
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"toller" wrote in message
...
I bought some 3/8" soft copper tubing, which fits the 3/8" compression
fittings just fine.

I also bought some 3/8" sweat elbows and Ts. They are way too big.

Presumably it is a matter of ID and OD being used for different components?
What size sweat fitting go with 3/8" soft copper?
What are the 3/8" sweat fittings for? I've never seen 3/8" hard copper.