Irish Rail has confirmed heating on board services from Longford to Connolly Station is operational.
It comes following several complains from rail users that carriages were not heated on Wednesday evening and Thursday morning of this week.
However in a statement Irish Rail say mechanical engineers checked both trains and will continue to monitor them for any problems.
Meanwhile some passengers were forced to stand on board the 06:40 Longford-Connolly train on Wednesday morning due to overcrowded carriages.
Iarnrod Eireann say the train operated at a reduced capacity, with 70 seats less as a result of mechanical fault.
It's understood the train departed this morning will full capacity.