Hi, I'm new to this forum

Now is summer and air conditioning naturally come to the rescue.
But there was a problem.
As It's worked quite normal air conditioner blowing cool, no matter how long, sometimes after 5 minutes
another time after 50 minutes, suddenly from air pipes began to blow heat! horror!

how i handle this situation for now.

At this point, after turning off the fan for a while, and then turn on the fan again, and then move less
degrees up and down.

Then everything becomes a normal, again began blowing cold, so until to the next time.
where to look for the problem? can anyone help me with advice?

The car is Fabia 1.4 mpi

It makes me think of a faulty sensor or possibly a control flap that's moving by itself; either way you need a VCDS analysis.

Firstly thanks for the answer KenONeill

 

"the possibly a control flap that's moving by itself" - it seems to me more likely because tests on obd2 interface show no errors.
But where is this control flap? how is it managed, What drives  that "control flap" ? how to reach it?

Well if it is autoAC then it might just be the temperature ontrol flap motor, maybe demand Lo>Hi>Lo>Hi uite  few times as that can help to clean up that flap motor's positional feedback track - that is if changing temperature a bit usually fixes it for some time.  Now if it is operating in the way that this thread title describes correctly, then maybe use the "search" on this section of this forum.

 

Edit:- but does your OBD2 scan tool have the ability to check the other controllers in VAG cars?

Edited 6 July, 20169 yr by rum4mo

The worst thing is that the problem is not permanent and appears occasionally randomly.
This doesn't gives me the opportunity to objectify point which unit is malfunctioning.
1.accidentally stopping the climate unit, 2.stepper motor for control flap, 3. or a mechanical failure of the control flap?

Usually it's happened on the road and not be able to stop the car and lifted the lid to survey.
OBD2 scan tool does not help me much. Most often I've used Bluetooth ELM327 OBD dongle and Android program (I know that this is not the best way), and once VCDS by USB cable, not shown me wrong.

If you can use VCDS, then I'd expect some flap motor error faults to be getting logged if it was due to them being intermittently faulty.

 

One thing to check for, an you hear any "knocking" going on, on the VW Passat it was known as the "clock ticking" - that is caused by the temperature flap motor "hunting" trying to find the correct position, actually other flap motors will also make that sound when "hunting" - that word just means that the motor is being driven to the wrong demanded position by the climaire controller and it is normally due to the flap motor positional feedback signal being intermittent.

The problem was localized.
After consecutive test by OBD2 scanner clearly define: "flap motor error faults", there is no doubt where the problem lies.
But Removal of this damage turns out to be very demanding and I can not find a master who to hire to disassemble entire control console to reach the said motor.