Hi,

So my vw polo 2005 (pre face lift) 1.2 polo twist a/c started blowing warm air and with a weak air flow  last year. I topped it up to the 30kpa pressure. Still didn't do anything. Took it to the garage, they regassed it and said they tested it for leaks showing no issues and that all the components seemed to be in working order. Drove it home and it was a bit colder but that lasted about a month.

 

Today I decided to do a bit of digging myself, the a/c compressor is spinning, no errors showed up on my scan tool and changed the cabin filter as that hadn't been changed in a while. Thought I'd check When checking the pressure on the low side, I did notice that the engine revved up and when it stopped the pressure would drop and build up again. Is that normal?
Looked at the fan to see if that was the problem. I thought the fan was supposed to be continually on when the a/c is on, but that doesn't appear to be the case. It switches off every minute or so and then turns back on, but doesn't appear to be spinning that quickly. There are no bad odeurs coming from the vents or leaks from under the dashboard, so I'm hoping the evaporater is still in good shape.

Any advice on what it might be Or any recommended a/c specialists in the North London area would be appreciated.

Thanks in advance for your help.

1 hour ago, sray said:

I thought the fan was supposed to be continually on when the a/c is on, but that doesn't appear to be the case

 

When engine coolant temperature isn't triggering the fan activation, what does trigger it is refrigerant pressure as read by the high pressure sensor G65.  From memory, low speed fan action should be triggered when pressure is >9 bar, high speed fan action at >16 bar.  Does your scan tool allow observation of G65 pressure output? That would appear as a measuring block in the HVAC module.  If you can view it, see if the fan action correlates with these pressures (switch-off numbers are lower for hysteresis; <6.3 bar and <12 bar respectively).

 

The problem may be that the refrigerant pressure isn't staying at these levels (for some reason), and therefore the cooling capacity is limited.

 

 

Edited 16 June, 20224 yr by Pete1

20 minutes ago, Pete1 said:

 

When engine coolant temperature isn't triggering the fan activation, what does trigger it is refrigerant pressure as read by the high pressure sensor G65.  From memory, low speed fan action should be triggered when pressure is >9 bar, high speed fan action at >16 bar.  Does your scan tool allow observation of G65 pressure output? That would appear as a measuring block in the HVAC module.  If you can view it, see if the fan action correlates with these pressures (switch-off numbers are lower for hysteresis; <6.3 bar and <12 bar respectively).

 

The problem may be that the refrigerant pressure isn't staying at these levels (for some reason), and therefore the cooling capacity is limited.

 

 

Hi Pete,

 

I will admit that I do have a very basic pro scan v400 which I pretty much just use for reading engine codes and resetting the service light. With the Hvac system it only reads fault codes that come up and doesn't allow me to observe G65 pressure output. Thank you for the info on the pressures.

Stephen