I think I might have a faulty thermostat on the above vehicle, as I don't seem to get anything other than warm air coming into the cab.

Does anyone have any links to videos on how to renew the thermostat on the model?

834 / 5,000

Which sensor do you have in mind when you call it "above vehicle". I assume you mean the ambient temperature sensor/thermostat located in the front bumper.

If the sensor in question is not connected, it displays this error:

21605 - Sensor for Ambient Air Temperature (G17) P0070 00 [00100111] - Malfunction

This is what the external sensor looks like:

The data should be located in:

Proceed as follows:

1 – Engine off, ignition off, connect your cable to the computer then connect the other end to the diagnostic socket of your vehicle.

2 – Switch on the ignition then launch the VCDS program. Go to:

3 – Click on “select" on Select Control Module menu.

4 – Click on “01 – Engine”.

5 – Click on “Adv. Meas. Values”.

6 – Select and tick the parameters that should display the outside temperature:

IDE00556 - Outside temperature

ENG103910 - Ambient temperature

Perhaps I should have been more specific.

I meant the thermostat in the coolant system within the engine.

I don't think it is providing enough heat inside the cab.

This is more focused information, but it's still not enough for anything more detailed.....

I think it will be necessary to check the essentials!

1. Does the engine have enough coolant. (engine problems)

2. Does the engine heat up and in what time (yes - no, normal - very slowly, engine problem, coolant pump or engine thermostat valve problem)

3. When adjusting the car's cabin temperature, do you feel transitions between hot and cold settings. (probably problems with the hot-cold flap control motor, could be something else)

4. Are there any errors present, check ????????

This video might help: https://www.youtube.com/watch?v=oezrEvFqS1w

I have a couple of old cheap OBD readers, is one of them likely to find any faults to do with the heating system?

I took the car for a 30 ish mile run this morning. Outside temp was around 6.5c, so not too cold.

I believe there is an issue with heating in the cab. There is warm air coming from all vents as far as I can tell, but I do not think it is as warm as it should be.

I have a warranty for life on the car and have already contacted the warranty company and voiced my concerns. They have confirmed that it would be covered by the warranty should a fault be diagnosed, but I have to pay for the initial diagnosis and they may well reimburse me.

I am in two minds whether to wait until I can test it in very cold weather or put it in for investigation before it gets really cold.

One thing I did notice almost when I finished my test run is that the air being blown into the cab went much cooler, no matter how much I fiddled with the controls.

As soon as I parked up at home, I checked again and still very cool air (not chilly) being blown into the cab. Until almost finishing the journey, I could feel heat, but not what I would expect based on previous cars I have owned.

I was warm enough whilst in the car, but was very well wrapped up with thermals etc.

Maybe next time I do a test on a much colder day, I won't wear so much.

If I can find a thermometer, I will put one in the cab.

I just connected one of my OBD devices which is a number of years old, and it did not detect any faults, but I doubt that it is capable of seeing them on this car.

Edited 30 November, 202530 Nov by dog-man

For comparison, the 1.5 tsi engine somehow warms up to a working temperature of about 90°C at an outside temperature of about 5°C at about 5km. The engine oil warms up later, reaching a temperature above 50°C is reached between about 10km, after about 25km the oil warms up to close to 90°C.

This data can be seen on the Instruments cluster:

The next step could be to somehow check the inlet and outlet temperatures of the coolant from the car cabin, in the case of hot pipes, the causes could be in the cabin. Then only the causes in the cabin remain, such as sensors, the other is the engine flaps for temperature regulation, control electronics,....

A long time ago I had an experience with the cabin temperature regulation, it worked once, the other time it didn't, with the air conditioning on it started blowing hot, when heating it started blowing cold at some point which would mean a breath of fresh air, hot or cooled. When connecting the vcds diagnostics, I found an error for the flap motor in the car's cabin.

For anything more specific, better diagnostics would be needed, sensor temperatures, values and positions of the flap motors,...

Certain sensors are also visible in the climate menu on Information Electr., which can be accessed by clicking on "menu" on the climate module.

Some basic diagnostic steps can be done using these menus.

This picture shows the connections that heat the cabin, if everything is ok one should be hot, the other slightly cooled. The hose connection should be located around the turbine.

Do the red arrows on the vents change colour if cold air is coming through?

I checked a little, as far as I know, these red or blue arrows change color depending on whether heating or cooling is set. In automatic mode, when the temperature is reached, cooler air could be gradually blown into the car cabin.

In any case, at current outside temperatures of about 5°C, when the heating is set to max, cold air should not blow and vice versa.

More than that without direct access to the car and checking or testing the sensors and flaps, I don't know how else I could help.

You have been very helpful.

I will check what I can again when I next do a longish run.

I think the reason for the cold air in the car cabin is the "AC" being turned on.

When the "AUTO" mode is turned on, the "AC" is also automatically turned on, which is supposed to remove moisture from the air conditioner's cooler while it is operating.

The resulting side effect is cooler air, while when the "AC" mode is turned off, warmer air is blown out.

2 minutes ago, Perb_bug said:

I think the reason for the cold air in the car cabin is the "AC" being turned on.

When the "AUTO" mode is turned on, the "AC" is also automatically turned on, which is supposed to remove moisture from the air conditioner's cooler while it is operating.

The resulting side effect is cooler air, while when the "AC" mode is turned off, warmer air is blown out.

No, that is not the case. I always check that the A/C is off to maximise heat.

I have been trying to find a guide to replacing the thermostat myself but found nothing so far.

I am not even sure exactly where the thermostat is located.

Which sensor exactly?

Information about the type of ventilation would be very helpful, single or 2 zone?

If I succeed, I will try to play around a bit with the elm327 adapter and free applications.... I promise nothing.

The main engine coolant thermostat.

In my Skoda Karoq 1.6 TDi SE it is dual zone, but I usually sync them.

Hmmm, just had a thought. I have only checked the airflow in the front of the cab.

Next time I do more than a local journey, I will check the rear passenger area to see if the airflow is barely lukewarm, same as the front.