A malfunctioning AC Metro rake carted a trainload of commuters to a car shed following an alleged “miscommunication” over the public address system at Dum Dum on Thursday, leaving them stranded in their compartments for 30 minutes without airconditioning.

The AC rake arrived at Dum Dum station at 11.31am. Hundreds of passengers waiting on the platform boarded it. The train, however, did not move for another 25 minutes.

According to a source, the passengers were asked to vacate the coaches over the public address system so the train could be taken to the car shed for repairs. The passengers did as instructed.

Lawyer Suman Chatterjee, who was on board, said there was a second announcement. After a while, the train doors re-opened, prompting many passengers to think that the train would run. “We assumed that the second announcement said that the train would run. All of us boarded the train again,” he said.

The doors shut after a couple of minutes but the train started moving towards the Noapara car shed.

“I was shocked when I noticed the train moving backwards instead of going towards Belgachhia,” said Chatterjee. “Some passengers were banging on the doors but there was nobody to listen to us.”

A CMC official, who was on the train, said: “Once the train reached the car shed, the AC was switched off. The passengers started panicking. Many were drenched in sweat.”

But don’t the motormen on board know if there are passengers inside? They do.

In an AC rake, there is a computer fitted on the dashboard in front of the driver which updates him about the total passenger weight.

Metro officials, however, said the passengers had been “unknowingly” taken to the car shed.

“There were only about 50 passengers, whom we requested to get down,” said Metro spokesperson Protyush Ghosh. “But there was some miscommunication and the passengers re-boarded the train. The drivers decided to leave for the car shed along with the passengers unknowingly.”