My SIL went in with her Fabia complaining that the aircon occasionaly blows hot for a good few seconds, then back to cold again. I have been noticing this with my Yeti, but thought it must be normal.. though I've never had it before in other cars.

The garage said to her that it needed to be investigated and it's now being fixed under manufacturers warranty.

I decided to ring them too (we got them from same dealership), and they said 'it's supposed to do that'.

Does anyone know which version to believe?

Self correcting feature of a computer contolled sytem?

Sit at the stern of a cross channel or in fact any ship with satellite guidance, watching the wake pattern the boat appears to 'tack' ever so slightly, maybe a similar selftest/correction?

I can see the logic there, but I don't remember any of our previous cars suddenly blasting us with hot air..

This is a common problem with fabias. The heater flap motor control fails or becomes unreliable, sending out hot air when cold is needed and vice versa. The heater matrix is always hot these days in modern cars, the flap sends the heat to waste if not needed as part of the cooling of the engine, or into the car if needed.

My wifes does this and as a 53 reg it is not worth the £250+ repair cost as the dashboard virtually has to be dismantled to reach the unit and the spare part is £80 on its own.

Even when repaired it often fails again within a couple of years.

We are living with the problem as the car is not worth enough now to fix, whether yours is or not is up to you. If it is within warranty definately get it done, but expect it to fail again.

Could be a temp sensor problem, I had a cold air situation on one side of the car, rectified by fitment of new sensor!