wasps in bedroon - ac retun leak?

Is there any way to check for tears in the AC "lines" (the tubes) from the inside? I think I have wasps in the attack and they have found a small tear in the "lines". Consistently only happens upstairs.
Have had AC company check, but some of the lines are buried in insulation and cannot be checked from outside. I have tried dusting attic for bugs but wasps seem pretty hard to kill off. Cannot see nest anywhere but they come and go around intersection of roof and "facings"
Hope this makes sense..
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