Engineers flown in from Europe to fix air conditioning on new Midland Metro trams

The fix is needed after it emerged the AC systems on the Spanish-made Urbos 3 trams were programmed to trigger at temperatures higher than those usually experienced in the UK.

Centro spokesman Mark Langford said: "We tend to experience a greater fluctuation in temperatures in this country than Spain, where the trams are manufactured.

"The thermostat on the trams has struggled to cope with the extremes of temperature, resulting in instances where the air conditioning is not operating.

"The trams are still under warranty and the issue will be resolved without incurring any additional costs."

Engineers are also seeking a permanent solution to remedy a failing set of doors on one tram.

Mr Langford said temporary repairs had been necessary to the doors on a tram on a recurring basis to allow it to stay in service.

The new trams have been phased into service over the past 12 months.