Intermittent aircon problem

[Aero]

Hi, we have a Fabia2 2009 . The problem with the a/c is intermittent and at the moment it is only working when the fan is on number 4. This lasted a few weeks last time and then it started to work perfectly in a normal fashion on any number. It was fine for a couple of months but as I said has now reverted to working only on Number four.
Any suggestions as to where to start to try and fix the problem ?
TIA

[J.R.]

Have the high & low side pressures tested with a guage set, failing that VCDS will give the high side pressure and any compressor shut off codes.

[AnnoyingPentium]

If it's only working on setting four then wouldn't that mean the resistor is on it's way out? Or have I misunderstood the original post?

[Aero]

Hi A P No, you haven't misunderstood . It only works on 4 but will periodicaly come back on all numbers for no apparent reason and be perfectly ok for maybe a couple of months and then revert to only working on 4. The resistor has been changed already.

 

J R  If it was pressure related then wouldn't the problem be constant ?  I don't have easy access to vcds. Cheers

[J.R.]

It is the first port of call for aircon diagnosis when a system is working but not efficiently.

[Aero]

JR, OK thank you for that . I'll see if the garage I usually go to can help in any way then