[H_Dogg72]

Discovered an interesting trait after owning my polo GT for 4 years. It has an always on AC compressor.

Remember the constant Tak Tak noise when ac kicks in? It just doesn't happen in VW's. What an epic thing to include in a cheap car.
I used to hate the ac in my Innova and wagon r which used to trip when the car was idle and I had to rev it to get the ac on.

The polo and ameo keep their AC on even when you're idling hours on end. No annoying Tak Tak.

I'm not sure if my creta has the same, not too bothered to check.
What about your car, how's the AC?
Furthermore did I open up any German car owners eyes to a beautiful feature they didn't know existed?

[Rshrey22]

It's basically an inverter compressor for cars. It doesn't get cut off from time to time, rather compresses at different speeds to adjust the temperature.

[sagarpadaki]

All modern cars have this feature. If the AC is ON, compressor is always ON. Hot and cold air are mixed to maintain the temperature in case of fully automatic AC systems where one can set the temperature.

[H_Dogg72]

Originally Posted by sagarpadaki

All modern cars have this feature. If the AC is ON, compressor is always ON. Hot and cold air are mixed to maintain the temperature in case of fully automatic AC systems where one can set the temperature.

Not all.
Regular car : compressor is either 0 or 100
Variable compressor: 0-10-20------100

Petty sure Hyundai cheaps out on this.
Furthermore my creta turns off the compressor when it reaches the set temperature, which is a huge nuisance. This does not happen in the VW's no matter what the temperature set, ac always on.
Both creta and VW have climate control btw.

[abhishek46]

I have a VW as well, the AC in mine, cuts outs and cuts in after some time. (With the same tak/tak sound as described above).
Not only that, when the AC starts/stops, i can feel a mild change in rpms as well.
Mine is a 7 year old Polo.

This variable thing may be a GT specific feature.

Anyways, regardless of what it is, I am happy with what I have got. Does the job!

[sagarpadaki]

Originally Posted by H_Dogg72

Not all.
Regular car : compressor is either 0 or 100
Variable compressor: 0-10-20------100

Petty sure Hyundai cheaps out on this.
Furthermore my creta turns off the compressor when it reaches the set temperature, which is a huge nuisance. This does not happen in the VW's no matter what the temperature set, ac always on.
Both creta and VW have climate control btw.

Ok, so you mean in the VW,that the compressor is operating at varying speeds to maintain the set temperature?

I have not observed the compressor cut in/out in our i20. Let me observe it more closely

[audioholic]

Originally Posted by H_Dogg72

Discovered an interesting trait after owning my polo GT for 4 years. It has an always on AC compressor.

Remember the constant Tak Tak noise when ac kicks in? It just doesn't happen in VW's. What an epic thing to include in a cheap car.

Can you explain how you arrived at this conclusion? Why would the AC compressor be running when not needed, ie when AC is switched off or when there is hard acceleration, or when the engine temperature is high? Have you studied the construction of the AC compressor?

The AC clutch might still exist, but be pretty silent so as to not cause a sound when it operates.

Originally Posted by sagarpadaki

All modern cars have this feature. If the AC is ON, compressor is always ON. Hot and cold air are mixed to maintain the temperature in case of fully automatic AC systems where one can set the temperature.

Not really. AC Compressor is controlled based on the refrigerant pressure and evaporator coil temperature and as a safety measure the engine coolant temperature. The cabin temperature is what is controlled by the mixture of hot and cold air. If the AC compressor was always running, then during hard driving it will result in excessive refrigerant pressure which can damage the system. Hence, the ECU operates compressor based on the above parameters. If the AC compressor runs continuously, then that will be the result of low refrigerant pressure due to which the cutoff pressure is never reached.

[Jeroen]

Originally Posted by audioholic

Can you explain how you arrived at this conclusion? Why would the AC compressor be running when not needed, ie when AC is switched off or when there is hard acceleration, or when the engine temperature is high? Have you studied the construction of the AC compressor?

The AC clutch might still exist, but be pretty silent so as to not cause a sound when it operates.

Agree, compressors do switch on and off, for many different reasons, even when on auto or whatever mode.In auto mode, most system do mix cold and ambient air constantly, so the compressor tends to run more or less all the time. But for various reasons it will still de-clutch.

I have four cars, all with AC and you can’t tell if the AC compressor is on or not by sound. You can observe to some extend a very small RPM drop when the compressor or clutch kicks in.

As far as I know all AC’s will be disabled below temperatures of 4oC irrespective of what the status of switches and or controls are.

Jeroen

[H_Dogg72]

Some info that will help cool the air.

" The pumps on most new generation cars eliminate the old fashioned clutch (unreliable, and a typical failure point of the AC system).

The Pumps are called VARIABLE DISPLACEMENT, CONSTANT PRESSURE pumps. They maintain a constant pressure by varying the volume of freon they push thru the system. The volume moving thru the system is determined by the expansion valve on the cabin evaporator, the expansion valve will open more as the fan moves more air across the evaporator thus increasing or decreasing the load on the engine.

When you select the AC to OFF, you don't really shut the AC off, what you are doing is commanding the pump to the ZERO output position of the internal mechanism (Swash plate). The pump in this position places less load on the engine than the older style heavy clutch spinning with the engines rpm's.

The front fans are a variable speed system. The fan speed is a function of condenser temperature and also pressure to a degree. The fans only pull enough air to displace the heat transferred to the condenser and back into the ambient air, again its a waste of energy to run the fans at anything more than required."

Links :
http://forums.tdiclub.com/showthread.php?t=461313

https://axleaddict.com/auto-repair/V...nt-Compressors