No cold air

Have you checked that the condensor fan is running too? Other than that you've done as much as you can unless you have access to VCDS to see if any faults are flagged?

There should only been 1 fan running when the engine is cold and with ECON on. This is the condensor fan.

My A6 aircon has also just stopped - no cold air and there isn't the usual noticeable drop in revs when switching econ on / off so I'm assuming the compressor isn't kicking in.

I've checked having read on here and the condenser fan isn't running (though the main engine fan did run straightaway).

Is the the non running condenser fan a sympton of the compressor not working or a cause ?

I've looked on vagcom under HVAC and no fault codes shown - but should I look under engine ?

Any tips for what to check next ?

nicknick said:

My A6 aircon has also just stopped - no cold air and there isn't the usual noticeable drop in revs when switching econ on / off so I'm assuming the compressor isn't kicking in.

I've checked having read on here and the condenser fan isn't running (though the main engine fan did run straightaway).

Is the the non running condenser fan a sympton of the compressor not working or a cause ?

I've looked on vagcom under HVAC and no fault codes shown - but should I look under engine ?

Any tips for what to check next ?

Click to expand...

Your engine fan should not be running straight away unless your engine is hot. Are you sure this isn't your condensor fan? It can be hard to tell which is which, especially as the engine uses both fans on some models.

If there's a fault that's actually preventing the compressor from working it will certainly be flagged in VCDS. In fact if the comprssor clutch hasn't kicked in I'd be surprised if a fault isn't flagged for this too. Have another check that the compressor clutch isn't working mate.

If the compressor isn't under a big load you may not notice a dip in revs.

Hi - thanks for the reply. My car (2.5 tdi) has main engine fan and then smaller fan on drivers side of car (on std UK RHD car).

The engine fan is on a viscous coupling but is running from idle. The aircon fan is not. I have tried swapping out the aircon control panel with another one but no difference. I can hear the relay under dash on drivers side click when I switch econ on to off.

I have VAGcom shareware version - no fault codes logged - I can read measuring blocks - any particular ones to check. Car is 1998 and has now done 175k so my expectation is compressor has failed (safe) and this is what is not allowing the fan to run ?

I can't think of anything else to try then mate to be honest. I don't know what blocks to try other than looking at what's available and going from there.

Have done a little more digging ..

Vagcom thinks the compressor is running. Measuring Block 001 shows this based on the following label file. Mine shows 0, and then 6 if I press ECON, or 7 if I turn it off. When driving if I put my foot down it shows 12 , which is off for 12 seconds when requested by engine.

None of the obvious issues I was expecting a fault code to be flagged for so I wonder if the fault is with the Fan ?

001,1,Comprossor,Shut-Off,Specification: 0 = Compressor Running
; 0 = Compressor Running
; 1 = Compressor OFF by Pressure Switch (F129): Refrigerant Pressure too High
; 2 = Compressor OFF by Fresh Air Blower (V2) or Fresh Air Blower Control Module (J126) Malfunction
; 3 = Compressor OFF by Pressure Switch (F129): Refrigerant Pressure too Low
; 5 = Compressor OFF by Missing Engine Speed Signal
; 6 = Compressor OFF by ECON Button
; 7 = Compressor OFF by OFF Button (via Fresh Air Blower Speed Buttons)
; 8 = Compressor OFF by Ambient Temperature below 3 °C (37 °F)
; 10 = Compressor OFF by Voltage below 9.5 V
; 11 = Compressor OFF by Coolant Temperature too High
; 12 = Compressor OFF by Engine OR Transmission Control Module
; 13 = Compressor OFF by Voltage above 17 V
; 14 = Compressor OFF by Evaporator Temperature
; 15 = Compressor OFF by Control Module Coding incorrect
; 16 = Compressor OFF by Climate Control Module (J255) Malfunction
; 17 = Compressor OFF by Pressure Sensor Malfunction
001,2,Engine Speed,recognized,Display Range: 0 = no/1 = yes
001,3,Vehicle Speed,,Display Range: 0...255 km/h
001,4,Standing Time,,Specification: 0...240 Min | 250 = Battery disconnected | 255 = Transfer Malfunction

If the fan isn't running for sure and of course the air con isn't even with the compressor running then it could well be the fan.

BUT if the compressor runs fine without the condensor fan running the low pressure cut out should trip eventually.

There are two fans - one big (on a viscous coupling, the other small and with an electrical connector. The big one is running - this is what I believe to be the main engine cooling fan. The smaller fan is what I believe to be the aircon fan. This doesn't run.

The compressor appears to run fine from VAGCOM - but if I feel the aircon pipes they don't really feel cold (one is warmer than the other). This and the fact that I used to be able to detect the drop in revs when the compressor cut in ( from econ) and now I can't which makes me question what VAG Com is telling me.

That said , will the fan really make a difference to temperature ? -I recently ( last 3-4 months) had the air con gas checked and temp was recorded as 7dC so on low it was really quite cold.

The fan will make a huge difference yes. The air con system won't work without it unless you're just relying on forced air from driving, but then when you stop driving there will be no air flow accross the condensor and then the LPCU will trip.

landopanda said:

Right just been out and checked to see if my compressor fan is working. Which it is, comes on and off with the ECON button. Does this then mean that the comprssor is bust?

Click to expand...

Not necessarily no. You've already said you can hear the clutch kicking in. But I don't really know mate. It could just need a good service.

My air con completely stopped working and my radiator fans etc turned out to be a little 30amp fuse located in tray ontop of the battery 2 mins to sort.