The A5/A483 Chirk Bypass will be shut between the Gledrid and the Halton roundabouts from 8pm until 6am on Tuesday, Wednesday and Thursday nights.
Traffic will be diverted through Chirk on the B5070.
Traffic Wales said the closure was essential to inspect the structural security of the Ceiriog viaduct which carries the traffic over the River Ceiriog.
Earlier this year there were closures of the bypass for major structural work to the bridge.
"The works are being carried out in September to avoid the summer holiday season but to take advantage of relatively good weather anticipated this time of year. Specialist access equipment is required to inspect the Viaduct," Traffic Wales said.
"The viaduct is exposed to prevailing weather conditions as it carries the A5 high above the River Ceiriog and its flood plains. The access equipment can only operate in low wind conditions."