I had the same problem too..... I have renewed all of the pods on the dash as part of a VW technician fk up (who'd have thought it for ?70PH)??...... this did not resolve the light flashing problem. Mine turned out to be the switch on the back of the fan, the connection from the 'loom' and the fan was intermittently losing connection and this trips the red light on , try looking at that, maybe try spraying it with elec contact spray and ensure that the contact is good/perminant.
Good luck!!!
Mix