Norwich — Major upgrades to the Thomas J. Dodd Memorial Stadium are awaiting negotiations between city officials and the team owners for a new lease or extension with the Connecticut Tigers, but Baseball Stadium Authority members are growing concerned that the heating and ventilation system at the stadium is failing.

The authority met at the stadium Wednesday prior to the Connecticut Tigers game and discussed stadium operations and maintenance needs. Authority member Gary Schnip, who oversees stadium operations, said various portions of the HVAC system have been failing regularly, and service calls for repairs are needed at least weekly, sometimes multiple times in a week.

Replacing the HVAC system, replacing stadium lights, which no longer meet Major League Baseball standards, with energy-efficient LED lights, and extending protective netting around the infield all are expected to be covered in an $800,000 bond approved by the City Council in spring.

But city officials made spending the bond money contingent on renewing the lease with the Connecticut Tigers minor league baseball affiliate of the Detroit Tigers. The current 10-year lease runs through the 2019 baseball season.

City Manager John Salomone, who did not attend Wednesday’s meeting, said later that the city’s version of a proposed draft new lease is in the hands of the city attorney and will be forwarded to Tigers’ officials soon. Salomone said the city is not looking for major changes to the lease.

While replacing the entire lighting system will be addressed in the bond, Schnip said workers will replace dead bulbs in the current lights this week, completing the task by Friday.

The Tigers are playing home games for the remainder of this week through Monday night.

c.bessette@theday.com