Net orders of Class 5-7 vehicles fell 3 percent in June due to a "large hiccup" in truck ordering, according to ACT Research's president.

The hiccup in medium-duty orders reduced the monthly net order volume to 14,700 units, which was well below the 19,300 units per month net order average experienced since last July, according to Kenny Vieth, president and senior analyst for the research firm.

However, medium-duty orders fell 3 percent year-over-year, so there may be a growing seasonal consideration for softer results in June, Vieth said. Seasonal adjustment is positive in June, boosting orders to 16,000 units.