Fabia, AC heater problem

[Odranreb]

Hi,

I'm writing here looking for help. 

Some weeks ago I bring my car to the near garage to recharge the AC, it stops working some weeks before: no cold air was produced.

While the cold air comes back the hot initially becomes weak, then completely stops. 

Now, no matter how long the engine is running, the AC system provides only cold air.

 

I check fuses and the level of cooling water. I read other posts in the forum and tried to look for air in the system with no result (I read a topic about let running the engine and AC without the coolant tank cap).

 

I have a normal AC, whitout digital display or controls. The fan work correctly and the button of AC light up normally. I change regularly the pollen filter. 

 

Have you some precious advice for me?

 

Thank you very much 

[Breezy_Pete]

A VCDS autoscan, or simple scan of the HVAC module (08) may indicate a fault with the V68 motor. This controls the flap which chooses whether incoming air is sent through the heater matrix or bypasses it.

Giving the flap motor a 'workout' by turning the temperature control from one extreme to the other several times while the system is running. See if that results in any hot air at any time.

 

[Odranreb]

Thank you very much, I'll try as sono as I can. Let you know the result

[Odranreb]

I try what you said and check the evaporator sensor, nothing change. Haven't much time to work on the car these days.

Yesterday when I start the engine a new noise came from behind the glove box, where is the air blower, like a "toc toc toc".

The car was cold and the external air colder (near zero).

What could have been?

 

 Thank you for your help

[rum4mo]

That "toc toc toc" noise sounds a lot like a flap motor hunting, ie it can not move to what it's positional feedback signal is the correct position - in some cars that noise gets called "the grandfather clock" noise.

 

From the position in the car that you are hearing this noise, I'd think that it will be the recirc'ng air flap motor which in my experience does also influence air flow through the heater box, though as wino suggests the air temperature flap valve is the one that is designed to control the temperature.

 

Can you stop the "toc toc toc" noise by demanding "recirc" - or even change that noise slightly, so that you could dismiss that flap motor?

[Odranreb]

On 30/11/2021 at 13:10, rum4mo said:

That "toc toc toc" noise sounds a lot like a flap motor hunting, ie it can not move to what it's positional feedback signal is the correct position - in some cars that noise gets called "the grandfather clock" noise.

 

From the position in the car that you are hearing this noise, I'd think that it will be the recirc'ng air flap motor which in my experience does also influence air flow through the heater box, though as wino suggests the air temperature flap valve is the one that is designed to control the temperature.

 

Can you stop the "toc toc toc" noise by demanding "recirc" - or even change that noise slightly, so that you could dismiss that flap motor?

Hi, thank you for your answear.

I try: the noise start when I turn the key, it get worst if  AC starts and stops if i demand "recirc". 

 

[Odranreb]

16 minutes ago, Odranreb said:

Hi, thank you for your answear.

I try: the noise start when I turn the key, it get worst if  AC starts and stops if i demand "recirc". 

 

Do I have to find and replace the part number 15 in photo?

[rum4mo]

That is the recirc flap motor V71, for a LHD car with auto AC is p/n 8Z1 819 453B, so yes repairing or replacing that part will stop the "toc toc toc" noises and hopefully improve the air movement and the temperature of the air coming into the cabin area.

[Odranreb]

I don't know how to thank you for your help and patience. I'll try and update the post.