AC stopped working just typical

[arthurd123]

First day of warm weather so I thought I could use the the AC and see if it’s still working. Skoda 2005 2.0 BKD with a climatronic dials. 

 

Taken it off ECON and boom nothing happened. I can usualy hear the compressor kicking in but not this time. The AC radiator fan doesn’t also not kick in.

 

Checked it on VCDS and there are no faults. I have few questions if anyone can answer that would be great.

 

Is there a way I can test the AC fan with VCDS?

 

Is there a fuse for both of these fans anywhere I could check?

 

Did measuring blocks on HVAC group 3 the electric fan value was 0.0 the coolant pressure was 6.8 bar I’m not sure what the correct value should be for those but it does sound like the electric fan has given up.

 

If anyone could help I would really appreciate it!

[Ju1ian1001]

It may just need a regas, if the gas has disapated to the elements then the compressor won't kick in and the AC rad fan won't kick in either. It's also a cheap fix if this is problem.

[arthurd123]

Hey Julian,

 

I was thinking that my self as well here are some logs from this morning, looks like my refrigerant pressure dropped as well:

 

Address 08: Auto HVAC  (1Z0 907 044 H)

06:58:36 Group 001: General
  0.0  Compressor Shut-Off Code
  800 /min  Engine Speed 
  0.0 km/h  Vehicle Speed 
  04:00  Standing Time 

06:58:36 Group 002: Compressor
  0.825 A  Compressor Current (actual)
  0.820 A  Compressor Current (specified)
  1000 /min  Compressor Rotations
  1.2 Nm  Compressor Load 

06:58:36 Group 003
  4.4 bar  Coolant Pressure
  0.0 %  Radiator Fan Activation (actual)
  0.0 %  Radiator Fan Activation (spec.)
  OFF   Engine Speed (increase)

 

 

[arthurd123]

Spoken to a AC guy today he said that my coolant pressure needs to be at least 7.0 bar for the the system to work correctly does anyone know if this is a true statement?

[PSM]

I seem to remember reading that you should keep the AC on all through the year as this helps to maintain seals and means the unit last longer etc. I also seem to remember reading that the systems will turn off the AC when it is colder anyway so you do not save much (if any) fuel by having it on Econ. I know on my limited tests I could see no difference in average mpg with the AC on or off (Econ on or off) so I just leave it on all the time now and let it kick in when it needs too.

Have the aircon system ever been regassed etc? if not then if it is probably due it after 13 years of use. I had my 2010 Octavia regassed when it was 6 or 7 years old. The unit was still working but did not seem to be getting as cold as it used to. Had it regassed and the system ran a lot better after and significantly cooler air coming out of the vents.

 

[KenONeill]

@arthurd123 - I couldn't swear to a system pressure, but the AC certainly should contain a specified mass of refrigerant. Given that note, @PSM has made true statements and ones that match my experience (including switching between Auto and Econ mode on a level road with the trip computer in instantaneous MPG to see if I got a noticeable change in MPG. I didn't).

[Breezy_Pete]

11 hours ago, arthurd123 said:

Spoken to a AC guy today he said that my coolant pressure needs to be at least 7.0 bar for the the system to work correctly does anyone know if this is a true statement?

 

Probably not. The Compressor shutoff code 0.0 means your compressor isn't being actively disabled, if refrigerant pressure were inhibiting function that would show 3 instead of 0, according to the list in this very useful thread about A/C problems: http://forums.ross-tech.com/showthread.php?633-Tis’-the-HVAC-Season

There's also a table of refrigerant pressures at various ambient temperatures in that link, note that this is with engine not running, and not having run for some while so the system is at ambient temperature. How long had the engine been running when you took the log info above?

AC fan should cut in as refrigerant pressure increases after system is running, threshold for low speed fan action is about 9 bar from memory, high speed if the pressure gets up to 16 bar.

[arthurd123]

3 minutes ago, Wino said:

 

Probably not. The Compressor shutoff code 0.0 means your compressor isn't being actively disabled, if refrigerant pressure were inhibiting function that would show 3 instead of 0, according to the list in this very useful thread about A/C problems: http://forums.ross-tech.com/showthread.php?633-Tis’-the-HVAC-Season

There's also a table of refrigerant pressures at various ambient temperatures in that link, note that this is with engine not running, and not having run for some while so the system is at ambient temperature. How long had the engine been running when you took the log info above?

AC fan should cut in as refrigerant pressure increases after system is running, threshold for low speed fan action is about 9 bar from memory, high speed if the pressure gets up to 16 bar.

 

Wino thanks for your info and the link I will check it out at lunch time...

 

I believe I drove the car to work it's a 7 mile trip so the engine would reach its optimal temperature. I then stopped in the car park and plugged in to take the readings off with the engine running.

 

I had the condenser replaced about 3-4 years ago by an independent AC specialist, re-gassed and serviced.

 

I was using the aircon during winter time too as I know you have to have it running during the cold months to keep the seals in tact.

[Breezy_Pete]

15 minutes ago, arthurd123 said:

I believe I drove the car to work it's a 7 mile trip so the engine would reach its optimal temperature. I then stopped in the car park and plugged in to take the readings off with the engine running.

In that case the refrigerant pressure does seem very low, I think. May not be the only problem though.

Check the pressure with engine off/ignition on, then go for a ten-minute drive with it switched on, then leave it idling; the lack of airflow through the condenser when idling should be enough to bring up the refrigerant pressure past the 9 bar fan activation threshold, I should think, after a while.  If you don't see fan activity at that point, I can look up fuse info etc.

Edited 20 April, 2018 by Wino

[arthurd123]

1 hour ago, Wino said:

In that case the refrigerant pressure does seem very low, I think. May not be the only problem though.

Check the pressure with engine off/ignition on, then go for a ten-minute drive with it switched on, then leave it idling; the lack of airflow through the condenser when idling should be enough to bring up the refrigerant pressure past the 9 bar fan activation threshold, I should think, after a while.  If you don't see fan activity at that point, I can look up fuse info etc.

 

Ok here it comes:

 

Ambient Engine off

 

11:32:03 Group 001: General
  5.0  Compressor Shut-Off Code
  0 /min  Engine Speed 
  0.0 km/h  Vehicle Speed 
  00:00  Standing Time 

11:32:03 Group 002: Compressor
  0.000 A  Compressor Current (actual)
  0.000 A  Compressor Current (specified)
  0 /min  Compressor Rotations
  0.0 Nm  Compressor Load 

11:32:03 Group 003
  5.6 bar  Coolant Pressure
  0.0 %  Radiator Fan Activation (actual)
  0.0 %  Radiator Fan Activation (spec.)
  OFF   Engine Speed (increase)
 

Ambient Engine on

 

11:32:39 Group 001: General
  0.0  Compressor Shut-Off Code
  800 /min  Engine Speed 
  0.0 km/h  Vehicle Speed 
  00:00  Standing Time 

11:32:39 Group 002: Compressor
  0.815 A  Compressor Current (actual)
  0.820 A  Compressor Current (specified)
  1000 /min  Compressor Rotations
  1.6 Nm  Compressor Load 

11:32:39 Group 003
  5.6 bar  Coolant Pressure
  0.0 %  Radiator Fan Activation (actual)
  0.0 %  Radiator Fan Activation (spec.)
  OFF   Engine Speed (increase)

 

After 10 minute drive 

 

13:07:02 Group 001: General
  0.0  Compressor Shut-Off Code
  800 /min  Engine Speed 
  0.0 km/h  Vehicle Speed 
  01:18  Standing Time 

13:07:02 Group 002: Compressor
  0.815 A  Compressor Current (actual)
  0.820 A  Compressor Current (specified)
  1000 /min  Compressor Rotations
  2.2 Nm  Compressor Load 

13:07:02 Group 003
  6.4 bar  Coolant Pressure
  0.0 %  Radiator Fan Activation (actual)
  0.0 %  Radiator Fan Activation (spec.)
  OFF   Engine Speed (increase)

 

In terms of fuses I have looked it up in the engine compartment position F38 10 Amp fuse according to the manual, the other diagram says F54 but this one is empty/fuse missing on my car. These are the fuses for the radiator fans that is.

[arthurd123]

Sat on idle for quiet some time:

 

13:18:37 Group 001: General
  0.0  Compressor Shut-Off Code
  800 /min  Engine Speed 
  0.0 km/h  Vehicle Speed 
  01:18  Standing Time 

13:18:37 Group 002: Compressor
  0.820 A  Compressor Current (actual)
  0.820 A  Compressor Current (specified)
  1000 /min  Compressor Rotations
  3.3 Nm  Compressor Load 

13:18:37 Group 003
  8.0 bar  Coolant Pressure
  0.0 %  Radiator Fan Activation (actual)
  0.0 %  Radiator Fan Activation (spec.)
  OFF   Engine Speed (increase)

[arthurd123]

Sat even longer at idle fan has kicked in as soon as it reached 9.0 bar, however there is no cold air coming through to the cabin.

 

13:26:40 Grou001: General
  0.0  Compressor Shut-Off Code
  800 /min  Engine Speed 
  0.0 km/h  Vehicle Speed 
  00:00  Standing Time 

13:26:40 Group 002: Compressor
  0.830 A  Compressor Current (actual)
  0.820 A  Compressor Current (specified)
  1000 /min  Compressor Rotations
  4.2 Nm  Compressor Load 

13:26:40 Group 003
  9.2 bar  Coolant Pressure
  0.0 %  Radiator Fan Activation (actual)
  32.8 %  Radiator Fan Activation (spec.)
  OFF   Engine Speed (increase)

[Breezy_Pete]

At least that rules out fan problems.

I guess either there's so little refrigerant that it can't meaningfully cool the incoming warm air, or there's a problem with the hot/cold air flap positioning.  Have a look to see if there's an adaptation procedure for checking/resetting that.  Might well be called V68 motor.

Could also be worth checking the resistance of the N280 control solenoid on the compressor, as described in the Vortex thread I think.

 

Edit: seems slightly strange that your log above doesn't seem to register that the fan is running? Unless that changed to match the specified just after that data was taken?

Edited 20 April, 2018 by Wino

[arthurd123]

16 minutes ago, Wino said:

At least that rules out fan problems.

I guess either there's so little refrigerant that it can't meaningfully cool the incoming warm air, or there's a problem with the hot/cold air flap positioning.  Have a look to see if there's an adaptation procedure for checking/resetting that.  Might well be called V68 motor.

Could also be worth checking the resistance of the N280 control solenoid on the compressor, as described in the Vortex thread I think.

 

Edit: seems slightly strange that your log above doesn't seem to register that the fan is running? Unless that changed to match the specified just after that data was taken?

 

Hey Wino thanks again.

 

 May I just add that only the bigger fan is spinning not the smaller one, that's how it's always been.

[Breezy_Pete]

Hmm, not sure that's right, can you see whether there's two or three wires going into the (smaller) fan motor itself? If two-speed, the low-speed resistor might have failed. If single speed it may have just failed completely. Pretty sure I'd expect them both to be on.

[arthurd123]

1 minute ago, Wino said:

Hmm, not sure that's right, can you see whether there's two or three wires going into the (smaller) fan motor itself? If two-speed, the low-speed resistor might have failed. If single speed it may have just failed completely. Pretty sure I'd expect them both to be on.

 

I''l take a look later on and I did the flap test inside the cabin by pressing ECON and one of the four buttons on top. It came back normal... 

 

The AC guy is coming to regas it next tuesday, I could take it to KwikFit but I don't trust these guys especially after an MOT issues I had with them.

[Breezy_Pete]

I'll have a look at wiring and fuse info for your car's fans in a bit.

[arthurd123]

1 minute ago, Wino said:

I'll have a look at wiring and fuse info for your car's fans in a bit.

 

Really appreciate your help I have posted on this before that only one of my fans is running when the aircon is running but didn't get anywhere with it. 

[Breezy_Pete]

No probs. Do you happen to know if the build date of your car is before or after 1st May 2005? (Different wiring documents either side)

[Breezy_Pete]

Seems like it's a two wire fan, probably speed controlled electronically. If you can get access, unplug the two-way connector that it is wired into, and measure resistance of the fan motor. High resistance might suggest failure.

[arthurd123]

1 hour ago, Wino said:

Seems like it's a two wire fan, probably speed controlled electronically. If you can get access, unplug the two-way connector that it is wired into, and measure resistance of the fan motor. High resistance might suggest failure.

 

 

Will drive home let it cool down and have a look afterwards thank you Wino!

[arthurd123]

23 hours ago, Wino said:

Seems like it's a two wire fan, probably speed controlled electronically. If you can get access, unplug the two-way connector that it is wired into, and measure resistance of the fan motor. High resistance might suggest failure.

 

I had a quick look yesterday and I can’t  reach the connector for the smaller fan as it’s on the radiator side of the panel, I have also read that it’s  better to raise the car remove undertray and release the whole panel through the bottom. 

 

My axle stand are at my mates garage so needn’t to grab them first, we can definitely rule out any fuses being bad too. 

Edited 21 April, 2018 by arthurd123
Spelling mistakes

[Aston_Bodger]

I had exactly the same on my VRS a couple of years ago.

 

It was the N280 valve on the compressor, it being a Valeo one I could not find a replacement valve , so I had to fit a new compressor, and it works fine now.

 

Had the shut off code as 0.0, so the compressor is working as far as the HVAC ECU is concerned, but In actual fact the air con in not working, not even the fans kicked in.

 

Hope this helps,

 

Trev

[arthurd123]

21 hours ago, Aston_Bodger said:

I had exactly the same on my VRS a couple of years ago.

 

It was the N280 valve on the compressor, it being a Valeo one I could not find a replacement valve , so I had to fit a new compressor, and it works fine now.

 

Had the shut off code as 0.0, so the compressor is working as far as the HVAC ECU is concerned, but In actual fact the air con in not working, not even the fans kicked in.

 

Hope this helps,

 

Trev

 

Thanks for the input Trev was your refrigerant pressure low too?

[Aston_Bodger]

No mine was spot on with refrigerant pressure.

 

If the compressor has gone they recommend changing the condenser too, done mine this time, as I could not get the drier pack from the dealers.

 

 

Trev