The most wonderful time of the year..........

[sepulchrave]

The fan malfunction will not prevent the A/C from working until it heatsoaks.

[Cheapas]

1 hour ago, sepulchrave said:

The fan malfunction will not prevent the A/C from working until it heatsoaks.

By heatsoaks do you mean the air con works up till it needs the fan to cool down the gas?

How does the fan work in relation to the air con? By that I mean the radiator is between the fan and the condenser, so how does the fan cool the condenser? 

[Breezy_Pete]

On 11/06/2021 at 10:16, Cheapas said:

The fault code (318) was the same as last year, and a Google around says it's a generic code across VAG  for low pressure

I've lost track of this thread a bit, but have you addressed this?  The system will be inhibited if the pressure sensor sees the pressure as being too low, often a sign of inadequate refrigerant quantity.

 

The reason I've focussed on the fan malfunction is that this is likely to be a contributing reason why you have lost gas rapidly since the last re-fill. If you don't fix this, when you do get it regassed, it'll leak out again just as fast, because the system pressures will be higher than if the fans were working properly. Higher pressure means faster leakage past any minor o-ring leaks.

 

The fans pull cool air from in front of the car through condenser, then radiator.

Edited 18 June, 2021 by Wino

[Cheapas]

Thanks Wino for the explanation. I wanted to check the low speed fan first as what you suggested made sense considering I'd gassed it up in May 20'.

Seemed pointless regassing before replacing fan.

The 318 code as you say seems to be a generic code for low pressure. 

Is the result I had from the bridging test a firm indication the fan motor is faulty, or are there any other things to try? 

If that's the case I'll replace the fan first, then move on to the low gas quantity.

On the issue of replacing the fan, a quick Google around and the likes of GSF are listing the fan either as a fan on its own or with a cradle/housing (with considerable price difference). Would you know if the fan can be replaced on its own , or would I need the complete item?

There are plenty on eBay, but if they are as fragile as you mentioned, maybe best to  swallow and buy new.

[Breezy_Pete]

With both the climatronic self-test and the thermoswitch connector bridging failing to get  the low speed of the fan working, I'd say it's pretty conclusive that the resistor within the fan has burnt out.  You've heard the relevant relay clicking in response to the bridging, so the only other thing that could stop it working is if the fuse was bust. You've checked that I seem to remember.

 

I would think the fan would be OK to replace separately to any other bits, can you post a photo of how it's mounted? Usually on a plastic tripod thing which screws onto the radiator/fan shroud with three T30 torx screws. Unplug the wiring at a connection near the bottom corner of the rad. Take that whole tripod with fan out and then the fan unbolts from the tripod bit from the other side.  Watch the torx bit goes fully into the screw heads before you apply force, the screws are often quite rusty and tear up easily.

 

There is a repair you can do by wiring in an external resistor, instead of replacing the fan, but it needs a bit of effort with wiring and metalwork. Much cheaper solution though.

[Cheapas]

Yes I had to move the block connector for the power supply to the fan to get to thermoswitch. Very limited access, also had to Google how to get connectors apart! Noticed most of the torx screws rusty, so this will be interesting, WD-40 time .

So plan will be get as much WD40 on screws tomorrow, then next Thursday on time off get  fan out and replace. Then try regas. 

I did read a thread on here regarding the  repair you mentioned, but think that's a bit beyond me.

There is a breakers near me, if they had a fan, would it be possible to test the 2 fan speeds with a jump pack ? Notice there are 3 cables into fan housing , would this be main power and a feed either low or high speed? If so , could run cable off positive cable on jump pack to fans main live, and negative to each of the other wires to test fan before buying? Or am I talking twaddle?

 

[Breezy_Pete]

You're close. 

Brown wire at pin 3 is the earth for both speeds, so battery negative to that pin, then put +12V direct on the middle pin (2) for low speed, move it to pin 1 for full power.

You'll get a bit of a spark when you make the + connections, and obviously make sure no fingers are in the way.

 

Edit, don't be too surprised if you find other fans with the same fault with low speed non-functional.

Edited 18 June, 2021 by Wino

[sepulchrave]

You could just rewire it to run full speed all the time, overcooling is not really an issue.

[Cheapas]

19 minutes ago, Wino said:

You're close. 

Brown wire at pin 3 is the earth for both speeds, so battery negative to that pin, then put +12V direct on the middle pin (2) for low speed, move it to pin 1 for full power.

You'll get a bit of a spark when you make the + connections, and obviously make sure no fingers are in the way.

 

Edit, don't be too surprised if you find other fans with the same fault with low speed non-functional.

Thanks Wino, think that's the reason for going down the route of buying new. Even if the used one is working, no guarantee it won't chuck up and back to square one.

 

8 minutes ago, sepulchrave said:

You could just rewire it to run full speed all the time, overcooling is not really an issue.

Reading Wino's posts/ advice , he's advising if I understand him correctly that doing this puts undo strain on the air con system, leading to leaks . Presumably over time of doing this , ie running fan all the time , would increase the leaks in the system , and eventually have to replace gas more often . I did think of your idea to save a few quid, but think I'll take the hit and change the fan, then see after regassing how long it lasts. 

After all the advice Wino's given me, it would be rude not to !

[Cheapas]

https://www.partsinmotion.co.uk/car-parts/cooling-heating/cooling-fan-assembly

Just checking, presume I'd need the bottom most expensive fan, due to the 2 power inputs as opposed to the other 2 which have just one power input? 

Edited 19 June, 2021 by Cheapas
Mistake

[Breezy_Pete]

You haven't quite understood me right. Doing nothing is what would potentially make the A/C work worse than it should, and possibly leak faster even after you get the refrigerant level right.

 

Sep's advising some sort of workaround whereby the fan would run at full speed when low speed is requested, I think, by swapping wires around.

 

Looking at the price of new fans on ebay, I'd be tempted to carry on with your scrapyard search.  Not every one will have failed, even though I think it's a very common fault.

 

Just to repeat, fixing the fan situation won't get the A/C working on its own, so maybe you're better off taking it to get regassed first, that way they'll find out if there's a 'show-stopper' that we haven't identified, like a big hole in something.

 

I think the fan part number you need is 6Q0959455N, a few options here: 6q0959455n | eBay

 

 

 

[Cheapas]

Thanks Wino.

Yes, I understand fixing the fan won't make the air con work. Presume there isn't a big hole in the system somewhere as a quick tap of a screwdriver on the refill port gives a hiss of gas. 

So, thinking out loud best if I get system regassed first and then if it holds pressure, move on to changing fan. 

If I run a bridging wire between the high and low speed wires on the thermoswitch, that would kick the fan in albeit at full speed when the air con system asks for it ?

Then if it all works, would have option of changing fan or being a bit economical with air con use and leave bridging wire in as per Sepulchraves suggestion.

[Breezy_Pete]

No, the radiator thermoswitch only triggers the fan according to coolant temperature, which isn't necessarily going to be what you need, cos that may not get hot enough for any fan action.

The A/C-related fan action is triggered by the Climatronic unit reading the refrigerant pressure using the sensor in the high pressure pipework. 

The fan control module has two sets of inputs, from radiator thermoswitch and from Climatronic module, either or both can make the fans go at either speed.

 

I don't know exactly what sep was thinking but possibly swapping low and high speed wires at the connector going to the fan itself? 

 

[KenONeill]

12 hours ago, Cheapas said:

There is a breakers near me, if they had a fan, would it be possible to test the 2 fan speeds with a jump pack ?

Odds are they'll have a jump pack, or a cludge involving several batteries in parallel that they use to demonstrate that horns, electric motors and the like do work before/at time of purchase.

[Cheapas]

21 minutes ago, KenONeill said:

Odds are they'll have a jump pack, or a cludge involving several batteries in parallel that they use to demonstrate that horns, electric motors and the like do work before/at time of purchase.

Good point. Obviously they wouldn't want numpties like me wiring their parts up myself !

 

1 hour ago, Wino said:

No, the radiator thermoswitch only triggers the fan according to coolant temperature, which isn't necessarily going to be what you need, cos that may not get hot enough for any fan action.

The A/C-related fan action is triggered by the Climatronic unit reading the refrigerant pressure using the sensor in the high pressure pipework. 

The fan control module has two sets of inputs, from radiator thermoswitch and from Climatronic module, either or both can make the fans go at either speed.

 

I don't know exactly what sep was thinking but possibly swapping low and high speed wires at the connector going to the fan itself? 

 

Thanks Wino. Tbh starting to feel a bit guilty taking up your time. 

I've reread your advice, particularly last post . 

So when the climatronic demands the fan, if I understand you correctly it goes for the slow speed fan first. If this slow  fan is not working, does the climatronic by default kick the high speed fan in?

 

[Breezy_Pete]

43 minutes ago, Cheapas said:

Good point. Obviously they wouldn't want numpties like me wiring their parts up myself !

 

Thanks Wino. Tbh starting to feel a bit guilty taking up your time. 

I've reread your advice, particularly last post . 

So when the climatronic demands the fan, if I understand you correctly it goes for the slow speed fan first. If this slow  fan is not working, does the climatronic by default kick the high speed fan in?

 

Yep, but only once the pressure is about twice as high as for low speed.

[Cheapas]

Thanks again. Just boxed it all up again , but before that pulled the block connector apart to the fan and ran pos and neg lead off battery to it . High speed fine but no low speed.

Had a look and doesn't look too tricky to maybe extract the fan itself without the cradle.

Next time off I'll look into getting pressure checked, Halfords are doing some sort of free check.

As an aside bought  this from Aldi a while back, £20, right handy  for undoing screws one handed on belly pan.

[Cheapas]

Well finally an update.

Finally after a fair amount of grief managed to source replacement fan. This turned out to be wrong fan but this morning finally  got right one. Decided to go for new one, as didn't want to end up with faulty used item. New one £94 ( ouch ) and that was with discount after they supplied wrong fan. Installed it, bridged wires , both fans working.

Bought STP guage and air con recharge bottle. I'd bought guage first, it showed system safe to recharge, so then  got gas.

Unfortunately this is not a happy ending as 2 pumps of the trigger put the guage into green charged section, then, with engine still running guage dropped into 0-5 psi section, indicating abnormal leak. Still warm air, and fan not kicking in.

So now with the engine off , guage attached, it reads 25-50 psi, fully charged. Start engine, and guage drops to 0-5 psi. Very puzzling.

Did another climatronic diagnostic check, fan kicks in full blast, on high setting, gradually slows to stop, not sure though if it tests slow speed while winding down.

Still showing fault codes 318 ( low pressure ) and 02. 

Bit stumped tbh, not sure where to go from here. 

[rum4mo]

That gauge/charging adaptor gets fitted to the low pressure side of the system, so you charging the system with the AC demanding max cooling aren't you? 

 

If so  then you have a leak in the system.

 

If the AC system has lost a lot of gas, you will need to demand cooling, which the system will not provide as the compressor will be left on minimum displacement, as you load in gas from your charging bottle, the system should get enables and start chilling the air - but if it is still reasonably leak proofed, a single small bottle of goodness knows what, will not return it to full capacity or maybe not even getting it running as a chiller as the pressure might still be too low due to lack of charge.

[Cheapas]

Thanks Rumo. Yes , while refilling had air con on on low, with recycle button on. In the photo of the guage, that's what it indicates attached to low port with engine off. 

Just this minute been out and attached guage again, needle in the green , charged zone. ( With engine off).

Presume if I had serious leak guage would be in red empty section.

And refill bottle still has plenty of gas, weird.

[J.R.]

You cannot rely on that guage, the low side pressure is directly proportional to the ambient temperature, if you are filling while the aircon pump is running (as you should) the low side pressure reading will be low.

 

Think of the system as having a low and high side (which it does) at rest the pressure is equal in both circuits and your guage reading should be compared to a temperature/pressure chart, when the system pumps the pressure in the high side goes up and of course the low side, the suction side of the pump will go down.

 

Pressure readings are very crude and need to be done with a manifold set reading both high and low circuits, the correct way to charge the system is by weight, I dont have refrigerant recovery equipment so have to rely on my guages but its very crude, in any case to judge when to stop filling its the high side pressure and to a lesser degree its relation to the low side that I will be looking at.

 

Today at 22°c I would be looking for 70-80 psi low side pressure with the system not having been running for at least an hour to enable the pump internals and the system to equalise to the ambient temperature.

 

The above pressures/temperature is for R134a, you are most likely trying to top it up with flammable iso-propane gas which will have a different temp/pressure graph, there is no way that you can guesstimate what the static pressure should be with your potentially explosive mix of gases.

 

As has been said one can is unlikely to fill your system anyway, they tell lies with the content weight often including the weight of the can, and in any case the nearer your system gets to the correct pressure the less you get out of each can, the final one unlikely to give more than 50% of its contents.

 

Frankly you would be better off without a guage as I was when like you I learned the hard way about these top up cans, I just kept filling and changing the cans until I heard the fans cut in & felt the system start to cool, that is only the minimum charge for the system to barely work, you need to add a lot more than that but have no way of knwoing when to stop.

[J.R.]

Having thought about it and after consulting my tables you should keep on filling with the aircon on full cold setting & blower fan on maximum until your guage reads 20-30 psi, when the engine is switched off the pressure would then rise to 70-80 psi if your outside temp is the same as here, look on t'internet for a graph or table.

 

what you have experienced is normal for when the pump starts working at the minimum gas pressure threshold, its normal for it to drop, keep on filling till it reaches 20-30 psi or 25-35 psi if ambient temp is above 30°c, you will likely need several cans.

[Cheapas]

Thanks JR . Annoyingly I'd planned to weigh the can before starting , but totally forgot. 

Back of the can does state it's R134 gas, it's not one of the cheaper eBay cans. 

Your stated pressure of 70 - 80 psi is according to the guage I've got is in the danger zone. 

But then as you say , how accurate is the guage? 

If the climatronic fault code is still showing low pressure fault code maybe I should ignore guage and carry on filling.

Current temp here is around 18 degrees. 

Edited 6 July, 2021 by Cheapas
Add picture

[Cheapas]

1 hour ago, J.R. said:

 

Ok, bit of detective work and trying to marry it up with your advice. 

Back of can says weight is 510g /18 oz. 

Air con label on car says 500g with a +-15g allowance. 

So taking all that in presumably if my system is very low as per climatronic fault code, 2 squirts of the trigger is not going to do it, regardless of what the guage says .

More like looking at the complete bottle minimum.

[Cheapas]

The bottle cost £59 with £10 back on return of bottle. Says  it can top up 3 cars ! 

Herein probably is my mistake, probably have been better to get car gassed up at garage and saved bottle for what it was designed for - top ups.