Had my temp set to 18C, and this morning it decided to blast me with hot air instead. Moved the dial up to middle, no change. To hottest, got a load of cold air. Back to minimum, still hot. So I suspected the dial was in reverse. Started turning it again to confirm, except now it's stuck on hot.

Finally arrived at work this morning following periodic opening of windows to let heat out (phew!) and played with the dial some more.

Turned on, with it set at minimum still. Cold air. Turned to hottest. Hot air. Turned to coldest, cold air.

Huh??? Any ideas?

You don't say whether you've got air con. But if so, it may be that your evaporator temperature sensor has gone... Don't forget, though, if you don't have it, the heater will just add varying amounts of heat to the ambient air that's coming in from outside, and if you do, the temperature on the dial isn't very accurate (i.e. if the temperature inside the car is very near what it's set on, you might get hot air or you might get cold...)

I do have air con. I switched it off because I wanted to know if that was the cause.

The dial might not be terribly accurate but the effect can be felt accurately enough to know that the heat was considerable at 18C.

This morning it was warm and somewhat stuffy hence I switched on the air con at 18C. To find hot air (not warm but hot) come out told me there was a problem. To find it come out cold when set to maximum confirmed that. Quite why the air then got stuck at hot beats me.

Just need to know if this is a common thing and what might be causing it.

Sounds like the sensor, then. Although if it does it when the air con's off, then it's not! If you can get hold of a member local to you with VAG-COM, then that ought to tell you for certain. The DIY sensor fix costs less than £25, although is quite tricky and takes about 40 minutes...

I would guess at a heater flap motor problem. A dealer or VAG Com scan will confirm as to whether this is the problem. You could try to see if setting it in basic settings works, otherwise I suspect that you will need a new heater flap motor.

Yeah flap motor all day long that one.

I would guess at a heater flap motor problem. A dealer or VAG Com scan will confirm as to whether this is the problem. You could try to see if setting it in basic settings works, otherwise I suspect that you will need a new heater flap motor.

Yeah flap motor all day long that one.

/\ Wot they said - they know much more than me!

When I had the same problem it was the flap motor

Can anyone tell me which part this is? I'm guessing it can't be an entire new heater...

Also, while today the heater operated the correctly, the air con decided to go AWOL. It kicked in while switching it on/off randomly half-way through my journey home.

I'm hopefully getting the ECU checked by a mate this weekend. Hopefully it will prove a simple fix...

On a Fabia the flaps which adjust air flow in the heater system (which on normal cars are cable operated IIRC) are moved by little electric motors. Sometimes these fail , causing the symptoms you describe. I cannot remember how much they are (I think there are 2 of them , it will probably be only one that has gone wrong) but theres a bit of labour to get some parts of the dash apart to remove/replace them.

they are under dash and attach to heater box they are two ,one v68 and one v157 easy fit but would need dealer to adapt.

if near hull call in at barkers and talk to andy cope(master tech)

My mate did a diagnostic check Saturday morning with Auto...something. Bear in mind his firm are diesel engine specialists as as such have that part of the subscription - the rest of the car has a basic output within the menus.

We have 04F7 Temperature flap control motor short to earth

And also 04F7 Temperature flap control motor short to B+

As someone stupidly decided to manufacture logging equipment without date/times, we cannot be certain when these occurred. He has asked me to return once it's happened again as he's cleared the memory and needs to see what new appears.

Now, interesting this lunchtime something weird happened. Had temp set to 18C with fan speed 2 and A/C on. In my journey, and without any changes by me, the heater kicked in and started blasting hot air at me. Within seconds it returned back to normal (good job too it was already warm in there).

It something getting stuck do you think or is there a sensor gone? My mate knows the right guy to fix it apparently but he tells me it'll save me £50 with the error codes already downloaded. Not sure the accuracy but works in the trade I don't. Either way something's obviously not right and I don't want to spent summer with heater stuck on full heat!

Your insights appreciated as always

The flap motor is what controls whether hot air from the heater matrix is added to the air coming into the cabin. Although you can't be sure when the faults occurred (not sure the car itself logs dates anyway!), your friend cleared the fault codes, which is sometimes enough to fix it as the motor can get its electronic knickers in a twist and play up as you describe. If that doesn't fix it, though (it looks perhaps as if it hasn't), then AIUI, the motor itself will need replacing...

Yeah the heater decided to switch to maximum by itself again today. My mate's around this evening (my birthday!) so I'll get his engineer contact's details and book it in I think.