I'd be interested to hear how your engineers reply to the tech log entries you make each time this happens.
Surely you have an Engineering technical services who meet regularly with flight ops to iron out exactly this sort of fleetwide problem?
Next time you fly, at the end of your sector after shutdown go to the MCDU press Menu > CFDS then bottom right LSK should be Print PFR.
Do that and post up any faults relating to the Hot Air Fault.
Or is it just that you're getting the ECAM message temporarily but no fault messages recorded?