Hi

My 2007 A4 only blows hot air from the vents when econ mode is turned on and the temperature is set to 16 degrees. Got a temperature gauge pointed at the vents today and they read 24 degrees when set to 16 degrees. 

The owners manual says that econ mode turns off the compressor. So that means I should be getting ambient cold air from the outside given it's a cold winters day. 

I had an independent mechanic plug the car into a diagnostic machine. He says that the shaft nut of the compressor is not turning when the clutch is on. While that is going to be an issue for me come summer time it is not my immediate concern. I would like to be able to regulate the temperature without using the a/c (whole idea of econ mode) but all I get is roasting hot air no matter what temp setting. 

Mechanic did a sequence test on all flaps and all was ok. 

Not sure what to do next. I have it provisionally booked into a main dealer a for diagnostic to see if the main dealer computer gives better information.  

Ultimately I will need to have the compressor repaired or replaced but that should be a separate issue to the blower problem as far as I am concerned based on what the owners manual says about econ mode. 

Any pointers would be greatly appreciated. 

Thanks. 

Hi Paul....welcome to the Forum

I would start with replacing = the compressor and a regas as will need replacing prior to the hot weather coming along.

After that, I would look at the system operation only because if the gas pressure is low and the compressor not working then the system will pretty much shut down to only allow basic operation of the HVAC system.

Let us know how this progresses

Cheers  Trevor

Thanks for your reply Trevor. 

This doesn't make sense to me however based on the fact that per the manufacturer econ mode = compressor off. If the compressor is off the fact that it is not working properly should be irrelevant. 

Am I missing something here?

thanks

Paul 

I see what you're saying Paul but what I mean is that if there is a fault with the system in any way then maybe start with fixing the fault and going from there.

 

I hear you Trevor. If a replacement compressor was a cheap and easy fix then I would just do that but cheap it ain't. 

I will get the compressor done regardless before the warm weather but it still doesn't explain 24 degree air coming through the vents on a 16 degree setting on a freezing cold day. 

There must be more to this particular issue than the compressor and so I don't want to address the problem in a back to front way. 

Thanks again for your input. 

Here are some A/C compressors for when you are ready to fit one...didn't think they were too bad price really...obviously plus a regas charge

http://www.audiownersclub.com/parts-results/A4-S4-RS4/A-C-Compressors--Clutches/33543

Thanks Trevor. I was quoted €700 for supply and fit which seems expensive. I know an auto a/c specialst who said repairs are possible depending on the issue. Either way he will likely be more competive than €700 for a new unit. 

ouch!  that's expensive!  I can see why you want to leave it until absolutely necessary (e.g.boiling hot summers days)