Air Con Troubles

[Dazza95]

I think there are two fuses, one normal blade type under a cover to the right of the strip fuses that does the low speed. See the Fuse sticky thread in the Fabia Tech guides section. what's your engine code, AMF? 

 

Just checked, Yep, fuse 8 on the battery, 30A blade.

 

Yes the engine code is AMF. The fuses on the battery looked quite dirty and greasy but nothing was broken.

 

Just to mention, I don't quite get what he's doing with the high-speed test on that vid. Not 100% sure it'll work like that on yours. As far as I can see, the pins you need to link are 1-2 for low speed, which is the one with a brown wire and the one with the brown/blue. For high speed you want to link 1-3, which is brown to brown/green. May need to wipe the wires a bit before you can see the colours. His wiring looks to be different in the vid.

 

You might also need the ignition to be on for both speeds. Try with it off first, but if nothing happens, try with it on.

 

Ta, like I said I don't think I've ever seen the fan work on low speed even when the AC was working; you could hear the fan clicking on and off quite loudly when the temperature knob wasn't turned all the way down (usually have it on 18c - 22c) or when it wasn't that warm. I didn't realise it had two speeds so I just thought the fan was cycling on and off due to low load or something.

Edited 4 May, 2016 by Dazza95

[Breezy_Pete]

Yes the engine code is AMF. The fuses on the battery looked quite dirty and greasy but nothing was broken.

 

 

Ta, like I said I don't think I've ever seen the fan work on low speed even when the AC was working; you could hear the fan clicking on and off quite loudly when the temperature knob wasn't turned all the way down (usually have it on 18c - 22c) or when it wasn't that warm. I didn't realise it had two speeds so I just thought the fan was cycling on and off due to low load or something.

Did you check the fuses under the cover to the right of the six strip fuses though? That's where fuse 8 is.

 

Top right corner of this pic (thick red wire's going to fuse 8, between the thinner red/green and red/white ones):

Edited 4 May, 2016 by Wino

[Dazza95]

Did you check the fuses under the cover to the right of the six strip fuses though? That's where fuse 8 is.

 

I see what you're saying now, I've only checked the strip fuse, I'll have a look tomorrow

[Dazza95]

I see what you're saying now, I've only checked the strip fuse, I'll have a look tomorrow

Just checked the fuse out and it looks fine to me. I'll test the fans on Saturday and check the wiring to the compressor, if I can't spot anything obvious I'll be off to the garage on Monday, can't be doing with the heat when I seem to spend most of my time on the motorway!

[Dazza95]

Struggled to get the connector out for the fans, so I'm asahamed to say I gave up. HOWEVER, I think I've found the cause of the problem. I followed the wiring from the N280 connection on the compressor and found a broken connector. See attached photos. I'll get this repaired but also get the fans checked out as I still don't they they work as they should.

On the downside, whilst under the car, I noticed the gearbox is leaking oil from the end seal :( this was refurbed ages ago and the garage reused the old seal.

Edited 7 May, 2016 by Dazza95

[Breezy_Pete]

As it happens, I shall be checking out my fans and AC-related wiring after a not-very-cold-when-needed experience yesterday on a long journey in the Polo with 4 adults and a small dog.

Not sure my first rad fan speed is working.

[Dazza95]

As it happens, I shall be checking out my fans and AC-related wiring after a not-very-cold-when-needed experience yesterday on a long journey in the Polo with 4 adults and a small dog.

Not sure my first rad fan speed is working.

Doesn't sound like fun! The compressor wiring has been fixed and the AC now works, the garage has tested the condenser fans - the control unit is sending the correct voltage for the low speed operation but the fan is only operating on high speed. New fan required.

Thank you all for the help

Edited 9 May, 2016 by Dazza95

[Dazza95]

Just viewing this on my laptop and have realised the photo of the connector hasn't uploaded.

 

I have attached the photo again just in case it helps anyone in the future. You just need to follow the wire fromt the compressor and you'll come to a connector as shown. The cable was broken but I didn't have the necessary tools etc. or skill to repair it myself.

 

The low speed fan issue doesn't actually bring up any error codes, however I can't imagine it will do the compressor any good cycling on and off with pressures in the system going higher than they be should be under normal use.

[Breezy_Pete]

Nice one, sorry to hear you're going to need a new fan though, how much is that going to be?

 

I've just been out with VCDS looking at my Polo and her Fabia  (both just sat idling with cabin fan on '2') to try to see why hers produces colder air.

 

Measuring blocks 1,2 and 3 on the HVAC module give you all sorts of info, and the notable differences were her evaporator (and outlet) temperature was a couple of degrees colder at about 6C, and the refrigerant pressure was lower, not going above about 12 bar, and her rad fans never went to fast speed. Mine kept cycling up to 16 bar when the rad fans spin up to high speed 'til the pressure drops down again, then the fans drop back to low speed and the pressure starts climbing again.

 

Looks like mine's having more trouble dumping the waste heat.  Might have to see about trying to clean some bugs out of the condenser fins?

 

Mine's been re-gassed much more recently than hers - last summer versus about four years ago with hers.

[Dazza95]

Nice one, sorry to hear you're going to need a new fan though, how much is that going to be?

 

I've just been out with VCDS looking at my Polo and her Fabia  (both just sat idling with cabin fan on '2') to try to see why hers produces colder air.

 

Measuring blocks 1,2 and 3 on the HVAC module give you all sorts of info, and the notable differences were her evaporator (and outlet) temperature was a couple of degrees colder at about 6C, and the refrigerant pressure was lower, not going above about 12 bar, and her rad fans never went to fast speed. Mine kept cycling up to 16 bar when the rad fans spin up to high speed 'til the pressure drops down again, then the fans drop back to low speed and the pressure starts climbing again.

 

Looks like mine's having more trouble dumping the waste heat.  Might have to see about trying to clean some bugs out of the condenser fins?

 

Mine's been re-gassed much more recently than hers - last summer versus about four years ago with hers.

 

Waiting on a quote for the fan as I need a few other things sorting such as the cambelt, CV gaitor and gearbox end seal.

 

With regards to your other issues I've seen similar symptoms on larger commerical systems and you'll be surprised at how much of a difference cleaning the condenser coils, checking filters and just making sure there aren't any restrictions to the airflow anywhere. You could also get it checked to make sure it has the right amount of gas and the high and low side pressures.

Edited 9 May, 2016 by Dazza95

[del-gti]

Think I may have a similar issue to you. My fan seems to only kick in at fast speed and as you said, doesn't show any fault codes for this.

My a/c would only work after the car had been sitting in the sun for a few hours and even then it wasn't cold. I suspect that pressure in the system increased due to the heat which allowed it to work. The other thing was that when it did work, there was that horrible hissing noise from behind the dash.

So I decided that if I could at least get the system correctly regassed, it would give me a baseline to work from, as I know that correct pressure is related to the system actually wanting to work. Well, lo and behold, it works. Ice cold a/c and no more hissing noise from the dash!

As I said though, the fan only goes from rest straight to high speed. I'm going to check the fan using the technique mentioned early, so I'll report back when I know more. I priced a replacement fan at about £65.

[Dazza95]

It's definitely worth checking, it's a well documented problem on some other VAG cars, see here:

http://forums.tdiclub.com/showthread.php?t=242699

[del-gti]

Well bit of an update on this - checked the fan today today via the plug and it would seem that the fan or more specifically, the fan resistor is at fault. Checking the low speed setting, there is an audible click (like a relay), when you connect the jumper wire but no fan movement. Fast speed works fine.

As you mentioned, this fault is well documented and seems to be very common. A bit more research has uncovered that there is a fix for the defective resistor but think I'd rather just save the hassle and buy a new fan.

I'm sure they've been posted before but here are the some pics of today's efforts.

The relevant plug:

Unplugged:

As it hasn't been used in quite a while, I bought a can of a/c purifier from halfords and stuck it in the car today to get rid of any bacteria and dodgy smells from the system. Nice smell, hopefully does the trick.

[Breezy_Pete]

Nice work, and nice photos.

The click you heard is a relay, inside the fan control module, which I guess you saw while you were in that area?

 

This thing:

 

Got a link to this resistor fix? Sounds interesting.

[del-gti]

Here you go: http://forums.vwvortex.com/showthread.php?4509806 Check out the links from post #3.

Now that I've had a chance to have a seat and do some more digging, I'm thinking about doing the resistor mod. Would be much cheaper and I could do most of the prep at work.

Yeah spotted the controller, much bigger than I was expecting. I'd only seen a pic of it when I was pricing a replacement, just in case.

[Breezy_Pete]

Much obliged. What a great post that #3 is. I fancy having a go at making a PWM controller from the last link, sounds cool.

Edited 15 May, 2016 by Wino

[rum4mo]

Much obliged. What a great post that #3 is. I fancy having a go at making a PWM controller from the last link, sounds cool.

 

It does seem a bit crazy in an energy efficient world that dropper resistors are being used.  Mind you, that method is cheap and can be made durable if implemented correctly, I do admit to using that method when we started to use SSRs with extremely small loads - in the interest of noise suppression and load separation!  The big issue when using these high wattage resistors is that the leads can end up getting a bit hot at the point where they are soldered onto the ends of these resistors - even if you have used heat sink paste and a decent heat sinking mounting plate. The original droppers will have used riveted or push on connections.

[Breezy_Pete]

Today's testing suggests my main fan doesn't work on low speed, and my small fan next to it doesn't work on high speed...

Gotta be a bad connection or busted wire for the latter I'd've thought?  Going back out for another look now the dog's been fed. :sun:

[Breezy_Pete]

Didn't get there again yesterday, but this morning I discovered that the small fan doesn't have twin speed functionality, there's only two wires coming out of the fan side of the three way connector for that one.  The slow speed on the main fan confirmed dead by measuring Ohms directly between the brown wire and red/white wire pins of its 3-way connector, and getting a very high reading - 250k or something.  I have a strong suspicion the missus's Fabia is in exactly the same state, there's only two wires to the small fan, and when AC is switched on only the small fan comes on (spins much faster than mine though  ) . 

[Dazza95]

Didn't get there again yesterday, but this morning I discovered that the small fan doesn't have twin speed functionality, there's only two wires coming out of the fan side of the three way connector for that one.  The slow speed on the main fan confirmed dead by measuring Ohms directly between the brown wire and red/white wire pins of its 3-way connector, and getting a very high reading - 250k or something.  I have a strong suspicion the missus's Fabia is in exactly the same state, there's only two wires to the small fan, and when AC is switched on only the small fan comes on (spins much faster than mine though  ) . 

 

It does make me wonder how many Fabias there are out there with fans not operating correctly. Mine is the newer design with just one large fan.

[del-gti]

Well that's mine fixed. Decided to go down the route of the resistor replacement to to see if that solved the problem.

So, I bought the resistor from RS Components, (RS Stock number: 188-087, P/N: HS 100 1RJ) and some thermal paste from eBay. Total cost £6.93.

Soldered some 14AWG wire on to each terminal of the resistor then added some heat-shrink, butted up to the ends of the resistor in a bid to keep out any water.

Then I found a piece of L-shaped aluminium in the scrap bin in work and secured the resistor to it. Now the guides I've seen online are for a mk4 Golf but there isn't as much room under the bonnet of a Fabia, especially with the 1.9 lump so I secured the resistor to the fan holder at the side of the fan, (I only have one fan). It does look a bit pikey but it's secure. Hopefully the fact that it mounted underneath the plate will protect it from the worst of the elements, also the bottom engine cover should keep the water out. I'll keep my eye on it and see how it weathers though.

Then I followed this guide to wire the resistor into the existing system: http://website.lineone.net/~alan.james.lorely/fan%20mod/Repair.html

The only difference is that I only have one fan, so only one resistor required. Also, of the three wires coming from the fan to the connector plug, one is brown and the other two are red - making it a little more difficult to select the right wire to cut. However, by following that the centre wire of the three is the one cut in the guide and also that on the other side of the plug, the centre wire is thinner than the other one - proving it's the low speed (7.5a vs 15a).

The connector, right hand side of this goes to fan:

Once it was all connected,I did the fan test again - success! Fan works in both slow and fast speed. Well happy, and a cheap fix too.

Edited 21 May, 2016 by del-gti

[Breezy_Pete]

Great work. :sun:

 

As a first fix I've got resistors coming for mine and the missus's cars.

Will probably copy your fitting arrangement.

[del-gti]

Good luck, keep us posted as to how you get on.

[Breezy_Pete]

Got my resistor(s) mounted on a spare ali plate:

 

 

 

That bolted up to a spare bit of angle, and the whole lot hung off one of the PAS module bracket bolts. Used two 0.47 Ohm 50W resistors in series 'cos they were 'in stock'.

 

Dodgy photo looking up from below:

 

 

It's a little closer to the PAS pipes than I'm completely happy with, so may tweak things a bit at the weekend when the car's up on ramps. Maybe I'll just put the plate the other way round on the angle bracket.

Edited 26 May, 2016 by Wino

[del-gti]

Nicely done. Fingers crossed you get it all sorted.