Octavia 3 estate 2016 form signature. AC is automatic, dual zone.

 

When temperature is set, for example, at 22°C, with outside temperature of 34°C and AUTO mode, driver side (left) is cooled as expected, but co-drivers side (right) is getting warmed.

 

AC is set like follows:

Temp: 22°C, sync

Mode: AUTO

 

Left side is cooled, right side gets hot air.

 

1. Checked for errors via OBDEleven and found B109515 (Position sensor for right temperature flap motor), intermittent. So I did calibration. Nothing changed.

 

2. Disassembled right side glove box and glove box frame, found the motor, took it out. During opening I didn't find anything strange, but while opening the potentiometer plastic case I broke it. So, this morning I bought replacement motor (5Q0 907 511 K) from wracked car. Put it in, no codes, but I still get hot air on right side.

 

3. Did a bit more detailed inspection using OBDEleven. Found out that I am not dreaming, right vent temperature sensor is showing 10-15°C more that the left one. To exclude the problem with those temperature sensors I switched their places (left to right, right to left). Nothing changed. 10-15°C hotter air on the right side.

 

 

 

4. I thought maybe the flap that is mixing air temperature for the right zone is mechanically broken. Disconnected motor, tried to move flap by hand and it moves like it should. Then, to be 100% sure, I got endoscopic camera and pushed it through one of the vents down the pipe and found the flap. While I am moving the lever by hand, flap is tracking my movements. It gores from end to end, without the problem. So, it is not mechanically broken or stuck.

 

https://www.youtube.com/watch?v=iqd4tCBjI-E

 

5. When I manually slow down the blower speed to 2 dots/bars, temperature difference between 2 zones get lower, but still, right one is blowing at least 5°C warmer air.

 

What could be the problem? Any ideas?

Edited 24 June, 20214 yr by Milentije

Does it do it when set to manual mode?

Yes, it is the same.

 

Only thing that makes difference is how fast the blower is blowing. If I set it manually to maximum than it is blowing warmer air to the co-driver zone. If I set it to blow slower (1 or 2 or 3 dots) than it blows cooler air, but still it is warmer than on the left zone.

Have you had the refrigerant changed recently? Also what pressure is shown on the compressor as you may be low on refrigerant.

I bought the car year ago. It is 4 and half years old now. I think nobody ever changed it.

 

I have to check if I can read compressor details via OBDEleven and will come back with data.

 

But, it is strange that I have problem only with one zone, and always the same one. I can't see how it can be due to refrigerant. Anyway, will check compressor data.

Edited 25 June, 20214 yr by Milentije

53 minutes ago, Milentije said:

But, it is strange that I have problem only with one zone, and always the same one. I can't see how it can be due to refrigerant.

I agree, and can't see how that could be due to refrigerant either. Still, with a 4.5 YO car, an air con recharge is probably wothwhile anyway.

Compressor is OK, as well as refrigerant.

 

Visited VW service today. When I told them what I have already checked they looked at me like I am coming from Mars.

Booked time slot in service for next week. I am really curious to see what is going on, but I am also prepared to here some bull**** from guys from service.

Will see.

 

 

AC system was filled up today with 135g of R1234YF. Now, it is almost snowing inside.

59 minutes ago, Milentije said:

AC system was filled up today with 135g of R1234YF. Now, it is almost snowing inside.

Thought it might be low refrigerant. Glad you got it sorted.

BTW What are your thoughts on moving to R134A? Draining (vacuuming) R1234YF and then filling the system with R134A?

 

1234 is insanely expensive, but it is not the worst part of it. It is so hard to find the service that can fill your system with R1234YF. For example, Skoda dealer doesn't have the filling machine, it was broken when I needed refilling. They sent me to VW dealer, but I had to wait more then 10 days there for my time slot in service.

At the end, I did it at Mazda dealer service same day.

You would need someone with both filling and recovery systems for both types of gas otherwise they will be venting the R1234YF to atmosphere, perhaps not a problem if it has been chosen as not being a greenhouse gas.

 

OTOH as expensive as it is anyone with R1234XY equipment should be delighted to recover your old gas FOC.

The charge ports are different and incompatible to prevent R134a being used in R1234yf systems. It is also illegal to do so, at least in the UK and across the EU.

 

If you manage to somehow do it and fill or partly fill your system with R134a, any R1234yf recovery machines will automatically stop and refuse to recover your gas as they have a system to check whether the gas is contaminated, so that might leave you scratching your head.

1. Suck out all the remaining R1234YF.

 

2. Fill up the system with R134A using connector converter.

 

I can read that many people are doing this. But, I can not see a lot of feedback after some time.

 

If you compare those two gasses, they are almost the same performance wise. Difference is in "environmental impact" and cost. Of course it will be stupidly expensive for no reason when DuPont has its hand in it.