Answer: The most common reasons for this vine not blooming would be lack of sunlight, overfertilizing (especially with nitrogen), and pruning at the wrong time. It does best in a hot sunny location with strong direct sun all day long. Overfertilizing can cause it to grow quickly with lush foliage but at the expense of blooming. This vine blooms on the new growth of the season, so you would avoid pruning it during the summer as this will remove the flowering wood.
If none of the above seem to fit, I should mention that Campsis radicans or trumpet vine is hardy into zone 4 and your zip code places you in zone 4A or the colder part of the zone. If your plant is in an especially cold microclimate or an exposed windy site, it may be that it takes longer for it to come into growth in the spring, thus shortening the growing season. This plant blooms on new wood of the season, and the new growth needs to reach a certain maturity before it can bloom. So a shortened season could mean it just doesn't quite have enough time.
I hope this helps you trouble shoot.
Q&A Library Searching Tips