Skoda Fabia I 1.9 SDI - The heating does not work

Hello

I have a problem that my Fabcia does not heat anything at all, i.e. it flies but cool air.
Engine temperature 90 degrees and here it is cold from the air vents.

I thought the thermostat, but the temperature indicator on the board shows normal.

Recently, I had the clutch pressure plate replaced, is it possible that during this repair I do not know, the system may have aerated?

I am asking for some hints

Broken linkage on the knob or on the air control flap.

1megan wrote:

Broken linkage on the knob or on the air control flap.

I apologize in advance for stupid questions, but I don't know anything about it.

The knobs seem to be fine, they do not jump in a strange way, the air blows sometimes harder and less depending on the setting of the knob.
It only blows cold air, not a bit of warm air.

And the heater tubes are both hot?

I don't really know where they are, I will search the internet and let me know.

See engine side. Two rubber hoses with a diameter of about 20 mm will enter the cabin through the bulkhead wall. Check them if they are hot when you are on the countertop 90 degrees.

under the pit, 2 pipes enter the bulkhead wall

Today I don't have the opportunity to check it, tomorrow I will test it as you advise.

Check the warm and cold flap actuator motor if it changes position. And the fluid level is not much too little. And as above, the snakes.

Fortunately, the system seems to have air in it, because I opened the coolant filler cap, it hissed air and ran out of fluid.
I have added liquid to the tank and the heating works as normal as before.