Hi all , require an experts advise please. the car has been into a skoda dealer . but no faults have been found.

this is the problem=

when ever the car is stationary with the air con on after after a short while it over presurizes which in turn causes the pressure relief valve to cut in and send clouds of white smoke from the engine bay.

The air con works fine all other times , that is I get cold air inside the car.

Now during pressure testing and measuring the system the fault occurs when the system reaches low side 4.8 bar and high pressure side 30 bar on the air con gas machine .......this is when it will vent the air con gas out.

the only thing obvious but i am not sure if i am correct in assuming this is :Are both or one of radiator fans meant to run or kick it when you have the air conditioning on??. on my car the only time the two fans work is when the water coolant temperature gets to high.!! no other time ........

Should this be the case??

i have looked on the vag.cat.com web site and i think it could be some thing to do with a faulty thrust sensor? (item number 14) But i am not sure as to what this does.

Any one there any ideas??

please advise , many thanks

Hi all , require an experts advise please. the car has been into a skoda dealer . but no faults have been found.

this is the problem=

when ever the car is stationary with the air con on after after a short while it over presurizes which in turn causes the pressure relief valve to cut in and send clouds of white smoke from the engine bay.

The air con works fine all other times , that is I get cold air inside the car.

Now during pressure testing and measuring the system the fault occurs when the system reaches low side 4.8 bar and high pressure side 30 bar on the air con gas machine .......this is when it will vent the air con gas out.

the only thing obvious but i am not sure if i am correct in assuming this is :Are both or one of radiator fans meant to run or kick it when you have the air conditioning on??. on my car the only time the two fans work is when the water coolant temperature gets to high.!! no other time ........

Should this be the case??

i have looked on the vag.cat.com web site and i think it could be some thing to do with a faulty thrust sensor? (item number 14) But i am not sure as to what this does.

Any one there any ideas??

please advise , many thanks

Both of the fans will come on at a lower speed when the air con is on as mine does in the Fabia.

My fans stopped working ant the local Skoda gargae had it in for 3 days testing and in the end it was both fans that were dead and they changed them and now it's fine, chaop said he hadn't come accross both going before, only on Golfs.

Not had my fans on for coolant temp reasons, but I think they will run alot faster.

AFAIK the fans should kick in and out when the aircon is on , so i think the fault may lie somewhere in that area, module/relay or suchlike

I think they stop and start as you 'stop and start' and stay off at normal speeds or they will impede the airflow through the radiators.

Does the air con have a PRV??

Never heard of a PRV on the air con as I certainly wouldn't want to chance breathing in the coolant gas... not good for you.

Thanks for your comments so far .

I am going to price up and ask about that thrust switch/ sensor at the dealers to see if they sell a few .I am sure that is the pressure sensor for the air conditioning. It perhaps switches the fans on when the pressure in the air con systems gets too high??

I know both my fans work when the engine coolant system gets too hot , but not work for the air con system .

Any one else can tell me or advise on this would much be appreciated.

Any expert on this come across this problem . I have heard that the fan control units are a problem on the vw cars at the minute. I dont believe its the air con compressor that is causing the problem of over pressure, or in fact the thrust sensor as it seems to be doing it job of killing the air con when the pressure gets to high.

got to be over heating related??

Any one out there advise??

This may not be much help to you but I will pass on what information I vaguely remember . . .

I am aware of problems with fans on VW Bora's (so guess Golf and other models too). Some (if not all) models should have a two speed fan (or was it two fans) but the motor burns out. The net result is you get a high-speed fan that pulsates on and off - instead of a low speed fan that stays on for longer. I don't think it causes any problems unless the fuse blows/main motor burns out - which may be more likely if the low-speed fan isn't working.

The fans are expensive to replace (don't think you can just replace the burn out motor) so it's worth finding an answer. I remember seeing a 'fix' to ensure the problem doesn't arrive / stays away - it involved creating and attaching a heat-sink to the car (a rectangle shaped piece of metal). I saw the info on "mk4forum" or something like that.

and