Air Con / C.c.

[Guest Dave S 194]

I'm new to this forum but have a strange problem with my air con that someone may be able to help with.

 

I've got a 2001 V6 auto with dual climate control, which until this week has worked OK. At the weekend when the outside temp was quite high the aircon stopped working and the C.C. just blew out uncooled air, which as it was in Auto it had the fans on max.

 

Then on Monday the air con worked in the morning but as the temp outside increased the aircon switched off again. By the evening when it was cooler it worked again.

 

I had noticed a couple of times recently that the C.C. display had flashed when starting the car and know that this means a fault in the system, but usually short on gas. So on Tuesday morning i took it to be gassed and on the way there the aircon worked. It was down on gas a bit, 850 instead of 1350, but by the time it was done the outside air temp was quite high at 32 C. The the aircon wouldn't come on and the garage couldn't find any obvious problem. On the way home the outside temp came down and when it got to 29.5 the aircon kicked in. I then noticed that when it went above 30 it stopped again.

 

I know there is meant to be a temp sensor to switch off the aircon if the temp is below 5 but didn't think there was one for if it's too hot. It seems that just when you need the air con the most, it goes off.

 

Can anyone shed any light on this?

[lazyb5]

Hi dave i dont know much but there is an ambient temperature sensor in the wiper area if this was faulty could possible turn off a/c possible loose wire other than that i am struggleing sorry :D

[Guest Dave S 194]

Thanks for the reply. I'll certainly have a look at the sensor, but i take it there is only one which provides the outside temp for the dash and CC. If so it's displaying the right temp, but i'm not sure what the onboard system does with the information. I saw in another post that it switches off the aircon below 5 C but have not seen anything suggesting there is an upper limit.

 

If anyone knows if there are upper and lower perameters in the system it would be useful to know (and if they can be changed). It looks like it will be another trip to the stealers to get them to plug their diagnostic in !! I'm getting to know them quite well now as this is the 8th problem in 9 months. :wacko:

[seatkid]

Are you sure you have dual cc? :wacko:

 

Dont confuse dual temp control with dual cc. The dual system has airvents in the head lining at the rear and is rare.

 

Seatkid said....There are two seperate refrigerant circuits for a dual system. If you have a dual system, you need to check both circuits for gas. The correct quantities are 950g for the front evaporator (single and dual cc) and 1350g for the rear evaporator (dual only)For each circuit there are two pressure switches - One is low pressure (not enough gas) - one is high pressure (too much gas or system fault). If you have a dual system there will be a pair for both circuits I think. Any of these switches can stop your system working.First check those quantities!

 

Note: The above information regarding two circuits is incorrect -

 

the correct info is

 

Single CC - 950g -single circuit one evaporator

Dual CC - 1350g - single circuit two evaporators

 

 

Its sounds as if the high pressure switch is operating. This could be a faulty switch, too much gas or lack of system cooling - make sure the cooling fan in the engine works as soon as you turn the cc on..

 

Above 30deg C the system automatically switches to recirc to improve its efficiency, maybe there is a problem with the recirc flap. Check and establish if recirc is working properly.

Edited July 7, 2006 by seatkid

[Masked Marauder]

Above 30deg C the system automatically switches to recirc to improve its efficiency, maybe there is a problem with the recirc flap. Check and establish if recirc is working properly.

 

And a sticking flap would give a flashing display too. When the temperature is over 30 have an assistant operate the "Econ" button whilst you listen in the engine bay for the compressor clutch clicking on and off.

 

It looks like it will be another trip to the stealers to get them to plug their diagnostic in !! I'm getting to know them quite well now as this is the 8th problem in 9 months. :wacko:

 

VAG-COM? You would have saved a packet by now!

[Guest Dave S 194]

Yes, it is dual CC as it does have the air vents in the roof. I had to travel a bit to find one with the highest spec when i bought it.

 

Didn't know there were 2 separate circuits but suppose makes sense. Not sure it was gassed properly on Tuesday as i think they only topped up one.

 

From what you have said it sounds like it's more to do with the system going into recirc mode above 30deg C, but difficult to check today as it's not that high. I think the compressor wasn't on above 30 C but came on when it dropped below 30 C.

 

I'll check out the recirc mode and see what happens, but suspect i'll have to wait for some more hot weather.

 

Thanks for your advice and yes i should have got VAG-COM or found someone near Thurrock, Essex who has it.

 

:wacko:

[seatkid]

Just double checked my information - I am wrong! :wacko: nothing new there then.....

 

Single cc - 950g

 

Dual cc - 1350g - single circuit!!!

 

So your refill was done correctly!

 

The pressure switch is a 3 way affair - so you have only one to measure high/low pressure.

 

or it could be a problem with the recirc flap or cooling fan or thermo switch.

 

 

 

Sorry! :wacko:

[raymac]

Can someone let me know once you have cold air coming in is it better then to leave the recirc on as you are recirculating already cool air which must be beneficial to the system as it does not have to cool down hot air being drawn in, i was told to do this by the aircon people who done my condenser/drier the other week :wacko:

[seatkid]

Yes if its hot outside, it can get cooler because it cools already cool cabin air. The downside is no fresh air - so after 30 mins you pass out due to lack of oxygen.... :wacko: .....thats why the cc will automatically cancel recirc mode after 20 mins :wacko:

[raymac]

Yes if its hot outside, it can get cooler because it cools already cool cabin air. The downside is no fresh air - so after 30 mins you pass out due to lack of oxygen.... ;) .....thats why the cc will automatically cancel recirc mode after 20 mins ;)

 

Cheers seatkid , so after the recirc has cancelled itself give it a few mins of outside air then on with the recirc again :wacko: just thinking that anyway of making the compressor /system work under a lighter load must be beneficial to the life of the system or are they just $hi** full stop :wacko:

[MrT]

If you have the luxury of a working air con, the air coming out the vents is around 45F, even when the temperature outside is around 90F, so there seems little benefit in recirculating the air as 45F is probably cold enough for most.

 

You also need to think that in hot weather the inlet for recirculation is just near your hot sweaty feet.

[Guest Dave S 194]

You were right seatkid. Took it to the local dealer yesterday afternoon and they traced it to a faulty pressure switch. They were able to replicate the fault and found that it also vented some gas at the same time. That's probably why it was down a bit on gas when i had it regassed.

 

They've had to order the switch as they don't have a parts dept and will fit it on Monday. I'll see if it fixes the problem but they seemed quite confident. They said

[Ogben Schmutzel]

Dave,

 

Do you know (does anyone know?) if the pressure switch venting gas is a part of its functionality or did it vent because in was leaking?

 

Cheers.

Oggy.

[Guest Dave S 194]

Oggy, It's meant to do that under certain conditions. From what the garage said it does it when it senses too much pressure, but they also said that temperature can make it do so. Maybe someone else may know why, but that's it's function.

 

The switch wasn't leaking but was was operating when it shouldn't, so hopefully a new switch may fix it.

[raymac]

If you have the luxury of a working air con, the air coming out the vents is around 45F, even when the temperature outside is around 90F, so there seems little benefit in recirculating the air as 45F is probably cold enough for most.

 

You also need to think that in hot weather the inlet for recirculation is just near your hot sweaty feet.

 

Mr T what i was trying to say was that the aircon man told me once the temp from vents was cool/cold then switch to recirc as it is easier for the system to cool air already cool than having to cool down air from outside that is hot and would make the systems work a lot easier :blink:

[Ogben Schmutzel]

Oggy, It's meant to do that under certain conditions. From what the garage said it does it when it senses too much pressure, but they also said that temperature can make it do so. Maybe someone else may know why, but that's it's function.

 

The switch wasn't leaking but was was operating when it shouldn't, so hopefully a new switch may fix it.

Ok, understood. I'm not disagreeing with you here but I thought other posts here have indicated that the role of the pressure switch is simply to turn off the compressor if the gas pressure is too high or low, presumably to prevent damage.

 

That it could vent gas makes sense to me but is not what I had understood from other posts.

 

Maybe its just me :blink:

 

Cheers.

Oggy

[Guest Dave S 194]

I mentioned that when it went in to have the pressure switch changed today. Was told it vents gas to reduce the pressure, but doesn't sound very environmentally friendly to me.

 

Anyway as an update, the new pressure switch was fitted and it made no difference. The aircon still switches off above 30deg C.

 

They are now working down the list of possible causes and have decided it's the control module. This is due to it switching off at 30 when it should automatically go into recirc mode.

 

I'm not conviced, but they are ordering the part, but can't tell me when it will be available.

 

So far i've only asked them to do a diagnostic and they've spent 5 hours on it and changed the pressure switch. They even delivered it back home afterwards.

 

:D

[Ogben Schmutzel]

Well at least you won't have to worry too much about it being over 30 C :D

 

Also, it will be a bit difficult to test won't it? Or is there a way of making the unit 'think' the temperature is over 30?

 

Cheers.

Oggy.

[seatkid]

Well at least you won't have to worry too much about it being over 30 C :D

 

Also, it will be a bit difficult to test won't it? Or is there a way of making the unit 'think' the temperature is over 30?

 

Cheers.

Oggy.

Yes hold the temperature sensor in your hand.......Who knows where it is? I think its somewhere near the dryer behind the bumper......

 

 

And why dont you short out the low temperature switch to at least eliminate that as the culprit.

[sepulchrave]

On a Mark 1 it is just behind the grille next to the o/s/f headlamp, you can see the wiring behind the bulb changing cover, you need to remove the grille to get it though. Don't know if they moved it on the Mark 2, no reason why they should really.