I re-gassed my AC a couple of months back and it has held pressure fine but over the past few hot days I have noticed that the aircon really isnt very effective. I can hear the compressor working and it shows up as around 80% percent compressor load in vagcom just the air doesn't feel very cold and it wont chill the cabin very much.

 

Could something not be functioning correctly or does the fabia just have pretty ineffective ac?

Edited 31 May, 20215 yr by JoeF

40 minutes ago, JoeF said:

Could something not be functioning correctly

Well yes, and it could be as simple as the cabin pollen filter needing changed. When was that last done?

Edited 31 May, 20215 yr by KenONeill
typo

38 minutes ago, KenONeill said:

Well yes, and it could be as simple as the cabin pollen filter needing changed. When was that last done?

Not for a long time. Although if it was the filter wouldn't it just not blow very powerful? Plenty of air comes out it is just not very cold.

Are the radiator fans working at both speeds? I should think a high proportion of cars this age have one or more fan faults unless work has been done since manufacture.

1 minute ago, Wino said:

Are the radiator fans working at both speeds? I should think a high proportion of cars this age have one or more fan faults unless work has been done since manufacture.

I don't think I have ever actually seen them spinning. Is there any easy way to test?

The car has never overheated since I have owned it so why would that effect the AC?

The fans help cool the aircon condenser irrespective of coolant temperature in the main radiator. Refrigerant pressure triggers fan activity at low or full speed as required, sensed by sensor G65. 

In ambient temperatures like we have had in the last day or two, switching on A/C set to minimum temperature should bring the radiator fans on at low speed within less than a minute from cold start at a standstill, I think.

Do you have VCDS?

Edited 31 May, 20215 yr by Wino
Missing word

4 minutes ago, Wino said:

Do you have VCDS?

Yes. Is it possible to switch the fans on with it?

Yes, one of the output tests in the HVAC module I think.

4 minutes ago, Wino said:

Yes, one of the output tests in the HVAC module I think.

Yep both fans do kick in on the self test.

I can't remember, do you get the option to try both low and full speed?

Just now, Wino said:

I can't remember, do you get the option to try both low and full speed?

It kicks in at full speed by the sounds of it then drops down to about half.

27 minutes ago, JoeF said:

Not for a long time

Worth doing then, if only because it will make both heater and A/C work better all year round. Lots of advice from @Wino on testing the radiator fans.

OK, so it sounds like all is well there.

Confirm that you do get them coming on shortly after switching on A/C too, in case the G65 sensor isn't playing nicely.

I took the filter out didn't look too bad but I will get a replacement. 

 

Tried it with the Aircon on and the small fan does kick in stage one according to the vag com.

 

 

 

Edited 31 May, 20215 yr by JoeF

Looks like main fan has suffered low speed failure. Very common. 

Either replace or repair with external power resistor. Guide in the "Handy topics and guides" section.

Edited 31 May, 20215 yr by Wino
Correction to subforum title

 

5 minutes ago, Wino said:

Looks like main fan has suffered low speed failure. Very common. 

Either replace or repair with external power resistor. Guide in the "Handy topics and guides" section.

Should they both be spinning at the same time?

Yes, wired in parallel.

3 minutes ago, Wino said:

Yes, wired in parallel.

I am going to be doing quite a lot of miles over this next week before I can get around to fixing it properly. Is there a way of me coding it so it always comes on at full power?

 

Is the compressor overheating and cutting out or just running at a lower power without both the fans?

Edited 31 May, 20215 yr by JoeF

Both fans should switch over to full speed if refrigerant pressure gets too high with just the small fan running at low speed, see if this happens after a while at a standstill. If it doesn't, check the strip fuses above battery.

 

You can watch refrigerant pressure in one of the HVAC measuring blocks. 9 bar threshold for low speed fans, 16 bar for full speed, from memory.

 

Catch you tomorrow.  

Edited 31 May, 20215 yr by Wino

8 minutes ago, JoeF said:

I am going to be doing quite a lot of miles over this next week before I can get around to fixing it properly. Is there a way of me coding it so it always comes on at full power?

 

Is the compressor overheating and cutting out or just running at a lower power without both the fans?

 

You could try adding some more gas to increase the cooling power, even without all the fans running properly the AC should get very cold before the system heatsoaks.

2 minutes ago, sepulchrave said:

 

You could try adding some more gas to increase the cooling power, even without all the fans running properly the AC should get very cold before the system heatsoaks.

 

Pressure seems to hover around 11-12 bar when in operation which as far as I know is correct?

High side pressures are dependant on ambient temperature and humidity, there is also a difference between the VCDS reading which I think is absolute pressure and the guage pressure reading from my A/C manifold set.

 

You start by measuring the system pressure with the engine not running and you compare that to the charts, if its too low then you need a top up, if thats OK then look at high side readings with the engine idling, AC and blower fans set to maximum cooling, you should see the high side pressure rise to somewhere above the region of what the graphs say (it depends on ambient temp) both fans should cut in and it should then stabilise at the graph pressure.

 

Doing it in the current hot temps is the best time to test, I am going to check mine tomorrow.

It's very difficult using home regas kits, commercial systems properly scavenge the system, then add the correct amount by weight according to the manufacturers specifications.

 

My hunch is you've been conservative with the quantity and should add gas a little at a time until it starts to get properly cold.

Ahhhhh, you regassed it with some Chinese butane gas canisters marked Environmentally friendly R134a equivalent?

 

That would explain a lot, if you did then have it vacuumed down & refilled using a proper R134a cylinder, something that is and does what it says on the tin. In the meantime dont use any naked flames.

 

Been there, done that!

Edited 31 May, 20215 yr by J.R.