AC starts automatically

[wide23]

Hi,

I my Polo AC starts working automatically when I turn fan ON by twisting fan knob.
Can it be adapted? I would like to turn setup AC manually by button AC only.

Best regards
Lucas

[iichel]

No this behaviour cannot be changed as far as i know

[CarbonChaos]

It is designed this way to be ‘on’ by default to keep the gas moving around the system ,if you don’t use it often enough the seals fail and you loose the gas.

[RUM4MO]

It is designed this way to be ‘on’ by default to keep the gas moving around the system ,if you don’t use it often enough the seals fail and you loose the gas.

I think that that is a very old fact, nowadays it is just a story, since the introduction variable displacement AC compressors, ie they don't have a clutch on the pulley, the AC compressor is always running and pumping, though it is only pumping a very low volume of refrigerant round the system to stop all plastic surfaces from "drying out" and so leaking.

In the case of Polo, these cars came with a variable displacement compressor since the 9N models, so mid/late 2001 in UK market.

For any VW Group car that I've owned since May 2000 and all had auto AC, the chiller is enabled by default initially, but once you have switched it off, even if the system is set on Auto, the next time you switch it on the chiller will be OFF, the only action that you take that will force the chiller to operate, is if you demand demisting, but even then, if you don't want it on, you can switch it off for the duration of that engine start and demisting on.

[CarbonChaos]

Please watch this video Rum4mo it’s very interesting , not a polo but a golf that’s 6 months old.

https://youtu.be/troc9DDaJkM?si=Cuezw3amFVTA0grM

[Le_Combattant]

It's normal.

If you switching "OFF" your fan with AC "ON", it wil automaticaly goes back to the last config when you will switch back ON the fan.

However, if (fan running) you switching OFF AC before the fan, when you will switch them back ON, AC will still OFF.

[RUM4MO]

Please watch this video Rum4mo it’s very interesting , not a polo but a golf that’s 6 months old.

https://youtu.be/troc9DDaJkM?si=Cuezw3amFVTA0grM

Very interesting!
I wonder when the car industry started adding back in a clutch into the AC compressor, maybe when R1234yf refrigerant started to get used, as in the case with R1234yf refrigerant, it does not have much in the way of ozone depleting powers, so now it doesn't matter for cars that have R1234yf if their AC system loses its charge due to seals drying out from lack of system oil being circulated around the system - the fuel and so emissions saved by adding a clutch back to these compressors have become more "important".

It can be strange how a car AC all round improver, ie a constant driven compressor but one has has variable displacement - ie a system that should survive a lot longer without losing its charge due to the plastics being continuously wetted, suddenly gets altered to improve efficiency - but brings back the old problem with gas being lost if the system is not used regularly - progress?? Well sort of - if you live in a warm/hot area of the world.

It was good to see a situation where the fault was intermittent, being solved, that sort of work is always more interesting, keep the brain used!

Edit:- just a thought, now if car makers were really interested in making sure that R1234yf losses due to lack of use were minimised, there would be timer-use monitor built into the AC controller that would engage that pulley clutch for short periods if the AC was not being used. I had heard that R1234yf gas losses were expected to be higher than R134a gas losses - but I hadn't heard why - now I know! Good business for workshops, but extra business that should never have been necessary.