Air Conditioning Pump Always On??

[m_ridzon]

I own a 2010 JSW TDI. I'm confused as to why the air conditioning pump appears to be always on. The system seems to be operating correctly. However, anytime I look at the A/C pump while the engine is running, the pump clutch appears to be engaged. No matter whether the dash switch is on or off, the pump clutch appears engaged.

I'm used to seeing older A/C pumps where the outer pulley rim engages/disengages with the A/C clutch. You can also hear older systems click when engaging/disengaging. Does my car have a different clutchless design? What starts and stops the flow of the R-134 if there's not a clutch engaging/disengaging on the pump?

[Conrad -JSW]

That's normal. In older cars the AC compressor is either on or off. Not so in these cars. The compressor is always on at some level.

[m_ridzon]

If the AC compressor is always on, then what is controlling the system? Cold air doesn't enter the interior unless I push the button on the dash. So what is taking place when I push that button? Is there some flow control valve that lets the R-134 begin flowing when I push the button? Or is there some other mechanism controlling the system?

[macscac]

It works the same way that light switches make bulbs come on.
magic.

[m_ridzon]

Bump.

Anybody know what controls the A/C system?? It's not controlled by a conventional pulley clutch like many older vehicles. Is there a flow control valve that starts/stops R-134 flow?

[GetMore]

Yes, there is some kind of system regulating the flow of refrigerant.
To be honest, I have not looked into how these systems work, so I can't add any more enlightenment, but that part I do know.

[Aonarch]

Should be pressure and temperature switches.

[m_ridzon]

Thanks for the info!

[dubidoobs]

Did your car come with climatronic or the conventional fan/ ac button?

Climatronic would be the only reason I can think of why the compressor is constantly running, because my wife's Accord has dual climate control and that's why her compressor is always running...of course I could be wrong

[m_ridzon]

My car did not come with climatronic. The pump is always running though. I think the system is controlled by some flow control valve somewhere in the system to start/stop R134 flow. Others have suggested that in this thread, and it seems to make sense.