The incident caused smoky conditions inside the market at 12th and Arch streets.
Firefighters simply unplugged the piece of equipment and began ventilating the large indoor market.
The Philadelphia Health Department was notified of the incident.
"Right now they're working with building management to make sure they're open (Friday)," said Philadelphia Fire Department Battalion Chief Mike Jackson.
The Easter weekend is one of the busiest for the Reading Terminal Market.
It is expected to be fully open at 8 a.m.
The Reading Terminal Market dates back to 1893, and is one of America's oldest public markets.