The present invention relates to a method for cleaning a heat exchanger (10). Said heat exchanger (10) comprises an inlet (12) which, during intended heating operation of the heat exchanger (10), is configured to receive a fluid, a plurality of channels (16) through which said fluid is arranged to flow for heating air passing between said channels (16) during said intended heating operation, and an outlet (14) for letting out the thus received fluid. The method comprises the steps of, during a cleaning operation, attaching a supply pipe (21) to said inlet (12) or outlet (14) for providing hot fluid to said heat exchanger (10); providing hot fluid through said supply pipe (21); and supplying pressurized air in pulses to said supply pipe (21) so as to provide said hot fluid to an increased flow rate through said plurality of channels (16) for cleaning said channels (16). The present invention also relates to an arrangement for cleaning a heat exchanger. The present invention also relates to a vehicle.