Puddle under car

[monkeyhanger]

All European spec. Polo(AW) have the compressor stays on in the background when blowing at the windscreen, even the LED light on the A/C button is OFF.

That makes more sense, the impression I was getting was others were saying it stayed on in the background under any setting - which didn't ring true.

It does stay on in the background on any setting if you believe what the convenience consumers screen is telling you. While the blower is on windscreen, the bar indicates a quarter of the full "1/4 gallon an hour", meaning about 1/16 of a gallon an hour is being used on aircon. When youvent forward or down towards occupants, the indicated amount of aircon use on the same screen is a lot lower but still indicating some aircon use.

[ho8882000]

All European spec. Polo(AW) have the compressor stays on in the background when blowing at the windscreen, even the LED light on the A/C button is OFF.

That makes more sense, the impression I was getting was others were saying it stayed on in the background under any setting - which didn't ring true.

It does stay on in the background on any setting if you believe what the convenience consumers screen is telling you. While the blower is on windscreen, the bar indicates a quarter of the full "1/4 gallon an hour", meaning about 1/16 of a gallon an hour is being used on aircon. When youvent forward or down towards occupants, the indicated amount of aircon use on the same screen is a lot lower but still indicating some aircon use.

I can't speak for every single Polo (AW), but I did a little experiment using VCDS on my 2019 Polo (AW) 1.6 Conceptline when it was still new from the factory without any coding changes. I use VCDS to access the Advance Measure Value "IDE00969 Compressor load (Nm)" of the 08-Auto HVAC control module, and I use this as an indicator to see if the compressor is switched ON/OFF:

I found the compressor will only stay ON in the background when blowing at the windscreen, no matter the LED of the A/C Button is ON/OFF.
But at other air blowing mode, the user have full control to switch ON/OFF the compressor.

I did the same experiment with my 2018 VW Caddy Crewbus 1.6 when it is brand new delivered from the factory, it gives the same result.

i.e. Both my Polo and Caddy have the most basic manual aircon, not the fancy climatic control aircon.

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On the other hand, the convenience consumers screen is also not lying to you.

If the air blower is blowing air at the driver, and the compressor is OFF (LED light of A/C button is OFF).
The car's air blower is consuming electricity, so the battery need to be charged, it is the alternator drive by a belt that charge the battery, and the belt is driven by the engine which consume fuels.

So, the convenience consumers screen is actually correct by showing the user that the car is consuming more fuel when the air blower is ON (Compressor OFF).

[RUM4MO]

While that must be true, in reality, the Sanden variable displacement directly driven AC compressor will never stop moving gas/fluid round the system, even when "OFF" as far as the car is concerned, it has been designed to operate at a minimum displacement of maybe only at 5% duty with the sole purpose of maintaining enough movement of system lubricating oil to keep all the system plastic seals and flexible plastic piping as close to being "leak tight" to the fridge gas as possible.

Edit:- operating in this way, has, in my experience, never ended up with ice forming on the evaporator - which when the car is stopped, turns back to water and drips down.

[ho8882000]

While that must be true, in reality, the Sanden variable displacement directly driven AC compressor will never stop moving gas/fluid round the system, even when "OFF" as far as the car is concerned, it has been designed to operate at a minimum displacement of maybe only at 5% duty with the sole purpose of maintaining enough movement of system lubricating oil to keep all the system plastic seals and flexible plastic piping as close to being "leak tight" to the fridge gas as possible.

Edit:- operating in this way, has, in my experience, never ended up with ice forming on the evaporator - which when the car is stopped, turns back to water and drips down.

I agree with you the Variable Displacement Compressor will always have 2% angle to circulate refrigerate around the system to lubricate the seals, this explain why you don't need to keep your compressor ON all the time to lubricate the seals.