It is very possible that the Evaporator behind the glovebox is leaking gas. - also, check the radiator fans.

one of mine are dead, and the evap is leaking, gonna have it replaced soon.

 

It is very possible that the Evaporator behind the glovebox is leaking gas. - also, check the radiator fans.

one of mine are dead, and the evap is leaking, gonna have it replaced soon.

Well my radiator fans work for cooling the engine, but when you put the AC on they dont come on. Initially VCDS didnt say anything, I Did the diagnostic and it came up as 0318 000 which according to the code sheet is the pressure sensor, having seen many posts about this being a fairly common fault I stuck a new one on. Thats when the system started working more, eg the compressor actually tried coming on but going off quite quickly, hooked up my recharge kit and the gauge was suggesting it was about the right pressure for the given temperature on the day.

All along though the fans didnt turn on continuous or anything which I'm sure on my other vehicles they do after about a minute or so when the system is running.

So it seems like the system is almost there, judging by how it apparently hadnt been used for years I would have thought the gas pressure would have been any, however it seems 'ok' (little bit less than my 98 T4 with icecold ac)

 

So thought I would add an update here. Still not working.

Fans do run when the engine is warm, not when the AC is on. The AC pump engages and spins, the gas pressure is apparently right, but no sign of cold air, would this soley be inhibited if the fans were not coming on?

From an AC point of view (as its part of my job) surely the AC would start but stop when the gas overpressured? meaning when moving you would have working AC, or am I missing something about the system?

 

When the AC turns itself off, you can read the shutoff reason using VCDS. It should be a number in one of the measurement blocks. Do that, then come back and we can diagnose it further. There is no point in trying to guess what may be wrong when you can check it

At least in my MK4 golf the compressor uses variable compression and compressor clutch never disengages. I don't know if all MK4s have similar compressor but when clutch disengages you can read the shut off reason and that should give you a clue about what is going on.

That said, the fans should turn on first speed when AC is enabled in climatronic.

- 0 = Compressor ON
- 1 = Compressor OFF: Refrigerant Pressure too high (> 32 bar)
- 2 = compressor OFF: Basic setting not performed
- 3 = Compressor OFF: Refrigerant Pressure too low (< 2.0 bar)
- 5 = Compressor OFF: Engine Start Detection
- 6 = Compressor OFF: ECON Mode active
- 7 = Compressor OFF: A/C System / FAN OFF
- 8 = Compressor OFF: Outside Temperature too low (< 3.0 °C)
- 10 = Compressor OFF: Vehicle System Voltage too low (< 10.1 V)
- 11 = Compressor OFF: Engine Temperature too high (> 118 °C)
- 12 = Compressor OFF: Shut-Off requested by Engine Control
- 13 = Compressor OFF: Vehicle System Voltage too high (> 17 V)
- 14 = Compressor OFF: Evaporator Temperature too low
- 16 = Compressor OFF: Compressor Activation faulty
- 17 = Compressor OFF: No or implausible Signal Pressure Sensor
- 18 = Compressor OFF: Vehicle Speed Shut-Off
- 19 = Compressor OFF: Shut-Off requested by Central Electronics Control (Load Management)

 

have it filled with a dye so you can check for leaks mate.... usually it leaks on the o rings in the system.... best course of action, find a place that is cheap enough and have them put a dye in it so you can pinpoint the leak... fix it and have it regassed.... you don't have problems with your filling points so it must be an o-ring causing the leak... this can be on the back of the compressor, on the dryer, on the internal radiator or on one of the other coupling points... i have yet to find a golf with airco/climatronic that has porous pipes.

 

When the AC turns itself off, you can read the shutoff reason using VCDS. It should be a number in one of the measurement blocks. Do that, then come back and we can diagnose it further. There is no point in trying to guess what may be wrong when you can check it

At least in my MK4 golf the compressor uses variable compression and compressor clutch never disengages. I don't know if all MK4s have similar compressor but when clutch disengages you can read the shut off reason and that should give you a clue about what is going on.

That said, the fans should turn on first speed when AC is enabled in climatronic.

- 0 = Compressor ON
- 1 = Compressor OFF: Refrigerant Pressure too high (> 32 bar)
- 2 = compressor OFF: Basic setting not performed
- 3 = Compressor OFF: Refrigerant Pressure too low (< 2.0 bar)
- 5 = Compressor OFF: Engine Start Detection
- 6 = Compressor OFF: ECON Mode active
- 7 = Compressor OFF: A/C System / FAN OFF
- 8 = Compressor OFF: Outside Temperature too low (< 3.0 °C)
- 10 = Compressor OFF: Vehicle System Voltage too low (< 10.1 V)
- 11 = Compressor OFF: Engine Temperature too high (> 118 °C)
- 12 = Compressor OFF: Shut-Off requested by Engine Control
- 13 = Compressor OFF: Vehicle System Voltage too high (> 17 V)
- 14 = Compressor OFF: Evaporator Temperature too low
- 16 = Compressor OFF: Compressor Activation faulty
- 17 = Compressor OFF: No or implausible Signal Pressure Sensor
- 18 = Compressor OFF: Vehicle Speed Shut-Off
- 19 = Compressor OFF: Shut-Off requested by Central Electronics Control (Load Management)

That looks pretty useful, under the HVAC any idea which things to press? Dont get me wrong I normally go through and find stuff, however I have found recently they have changed some stuff, so something like throttle adaptation on my T4, it was one process 2 years ago, the newer software the description says to do something else. Is it a live view only thing also?

have it filled with a dye so you can check for leaks mate.... usually it leaks on the o rings in the system.... best course of action, find a place that is cheap enough and have them put a dye in it so you can pinpoint the leak... fix it and have it regassed.... you don't have problems with your filling points so it must be an o-ring causing the leak... this can be on the back of the compressor, on the dryer, on the internal radiator or on one of the other coupling points... i have yet to find a golf with airco/climatronic that has porous pipes.

I'm not convinced gas pressure is actually the problem(yet), I've had a mk6 golf which had a slight leak (yet VW couldnt find a problem and they dyed the system) and you could tell when that had lost pressure, not just because it wasnt ice cold. I have a refill kit thing and according to the outside temperature at the time of testing, the gas pressure is right, turn the AC off, pressure goes through the roof, so from an AC perspective it looks about right. Its like its circulating the gas, but not actually doing the refrigeration process, so not using the control valve on the evaporator so the gas just circulates.

I have recently changed the AC system pressure switch on the bulkhead, before I changed it the AC compressor would come on briefly then go off again, like it was failing to start for some reason.

It wouldnt surprise me if the fan control switches are faulty or something. Kinda getting sick of the bugs on this mk4, had a Bora V5 and everything worked fine and that had just 82k on the clock 4 years ago including ICE cold A/C, this mk4 with just 72k I thought great, but I think some back street garage has been involved and consequently after it sat for 3 years in a garage they didnt really 'recommission' the car like VW would, they just mucked about with it, got some of it working and then the previous owners (who never used the AC, despite the fact the drivers window wind mechanism was FUBAR with all the hot summers we have had!). Kind of annoying when garages dont exactly know what they are doing or dont fix things properly, I have been even wondering if the AC compressor was part of the problem and had been stuck up.

Its typically non A/C weather today and is basically flooding everywhere, so I cant even go out with the Laptop to VCDS the thing and see if I can find any problems, supposed to be dry tomorrow night and someones dropping me off a sensor (to replace another part on the car thats failed, the lateral acceleration sensor, which the PO said some lights come on on the dash and some times they go out and dont always come on, so didnt bother to get it fixed!) so I want to swap stuff over and plug the laptop in and clear all the faults and see how it goes.

 

You go to measurement blocks, then read group 2 (I think it was group 2). It is a live view, it updates automatically.

I did not quite understand what you mean by A/C weather. A/C should turn on and function in any weather as long as outside temperature is above 3C. It does not matter if it rains or not. You will sit inside the car with the laptop so the rain should not bother you.

So you changed AC compressor because it was coming on and off? Now you have the same problem that it disengages after 5 seconds?

By the way, you can tell the AC is on also because the idle RPM would be raised when clutch engages. There is actually a place in measurement blocks where this can be seen also, but not relevant to your current situation I guess.

 

You go to measurement blocks, then read group 2 (I think it was group 2). It is a live view, it updates automatically.

I did not quite understand what you mean by A/C weather. A/C should turn on and function in any weather as long as outside temperature is above 3C. It does not matter if it rains or not. You will sit inside the car with the laptop so the rain should not bother you.

So you changed AC compressor because it was coming on and off? Now you have the same problem that it disengages after 5 seconds?

By the way, you can tell the AC is on also because the idle RPM would be raised when clutch engages. There is actually a place in measurement blocks where this can be seen also, but not relevant to your current situation I guess.

I thought 'LO' was like 15c or something, meaning if the temperature outside was like 12c like yesterday it doesnt run it, hence 'not AC weather'

I havent changed the AC compressor, I changed the pressure switch on the bulkhead, I had wondered if the compressor might have been a problem also, but it now seems to run more consistently, although its not clear if thats as a result of the pressure switch change.

When you turn the AC on you can hear the clutch engage and the revs dip fractionally for a moment and then go back to normal, I checked under the bonnet and the centre part of the AC pulley is engaged and spinning permanently until you turn the ac off.

Its looking dry today so might actually be able to get from the house to the car (20ft from the house), lastnight the rain was so hard I am surprised it didnt flood everywhere!

 

The fuse box on top of the battery could be stopping the fan coming on with the AC

I was looking on YouTube about the fuse box to fix my ABS errors and people were also reporting AC problems with it.

The ABS/AC fuses are the normal blade type on the right, in one video a cable tie was used to keep sideways pressure on a fuse to make the fan run.

The fuse boxes don't cost much, bought one off Amazon for under £15 which fixed my ABS problem.

 

No, as you can see from the VCDS info the low is under 3C

- 8 = Compressor OFF: Outside Temperature too low (< 3.0 °C)

You still need compressor as system needs to dehumidify the air. Otherwise you would have had foggy windows every time it rains. As a matter of fact if will be on even if you set maximum temperature in climatronic.

Ah, so you do not have compressor turning off after 5s anymore. In either case, you can check the temperatures and pressure using VCDS.

There is a hidden place where you can read the pressure switch value. If you have sensor type switch, you can read the pressure! It is in engine controller actually. Group 137

https://www.ross-tech.com/vag-com/m_blocks/130-137.html

By the way, at least in my car the idle RPM is ~800 but it goes to ~1000 once compressor engages. Unless if the engine is cold then it will have high idle RPM anyway until it warms up.

If you have a J293 fan control module, it could be damaged also. But perhaps fusebox is a good place to start yes.

There seem to be several fuses used for it:

https://forums.ross-tech.com/showthread.php?14597-mk4-Fan-Control-Module-(J293)-chart-and-A-C-tips

 

This Is really useful stuff guys, think I plenty to look at tonight

 

So I have had a look through everything, I cannot find what your describing under any section, which version of VAGcom are you using?

I had a couple of VW guys (not people from VW) come round tonight, quite in to their golfs and one of them said, do the fans come on ever in low speed. so the answer is no to that, which I hadnt come to a conclusion on why no yet. First thing one guy says is, I bet its a the fans are shot, low speed resistor goes on them. I have seen mention of this, but not actually done any testing on the fans. I have seen somewhere you can repair them, which I think I'll have to find 5 mins to do.

Other than that I couldnt find anyway to get output from the AC system that would tell me the pressures or anything, it would go through test sequences to make sure all the flaps worked, but thats about it.

 

Is the system pressurised properly? I mean properly, not with some can from Halfords.

 

Is the system pressurised properly? I mean properly, not with some can from Halfords.

You only need to check the system pressure, which the refill gauge I have can do perfectly fine. The only way to really do this properly is to have all the gas evacuated, replace all the seals, the drier, then put in the set 500g odd of refrigerant.

Personally I am not dicking about going that far yet, because until I know all the components work properly I'm not doing anything with the refrigerant gasses.

This is pretty similar to the Gauge I have:

The system when not running is round in the red, when running (as in the AC on) is somewhere around the 33-38 mark in the green zone(depending on outside temperature), but what doesnt happen is the low speed of the fans coming on. When the primary full speed of the fans come on it drops down to maybe about 27, so just in the green. On my T4, it does pretty much the same thing although there is a little more pressure in that, not much though.That would indicate its maybe a bit low on gas, however it should still be sufficient to make it cold and trigger the low speed fans, which never come on. On the T4 they come on after a couple of minutes, even when the engine still hasnt warmed up, not the case with my mk4!

Once I am certain they can be triggered and it works, then I know all the components are actually working how they should, then I will look at the gas charge again.

 

So I have had a look through everything, I cannot find what your describing under any section, which version of VAGcom are you using?

I don't understand how you can't find it. It is almost like you used VCDS but it showed you an empty screen Because you did not even mention did you find any sensor readings?

I use VCDS lite but it is all the same you go to measurement blocks. You should see something like this (I found this picture online):



You may either have the pressure in climatronic or in engine. If in engine the group is 137 I think.

You should also see things like evaporator temperature, calculated temperature, etc. Not sure if condenser temperature can be seen...

I think you should be able to see if the fans are activated or not. It is all in there, you don't have to get out of the car to diagnose it

 

I don't understand how you can't find it. It is almost like you used VCDS but it showed you an empty screen Because you did not even mention did you find any sensor readings?

I use VCDS lite but it is all the same you go to measurement blocks. You should see something like this (I found this picture online):


You may either have the pressure in climatronic or in engine. If in engine the group is 137 I think.

You should also see things like evaporator temperature, calculated temperature, etc. Not sure if condenser temperature can be seen...
I think you should be able to see if the fans are activated or not. It is all in there, you don't have to get out of the car to diagnose it

Yeah it doesn't look quite like that, I see that picture is from version 11.11.4, mine like 19.1.3 or something, I have found they have changed a load of stuff, at least it seems as I been using vcds for about 10 years or so, so like to do throttle adaptation you did one thing and a series of pressing the accelerator pedal and not to do it, it doesn't do it anymore, in the same way I am trying to bleed the brakes on my t4 with the abs stuff and it's having none of it. I might have a much earlier version on disc, going to try putting that on and see if the software might be part of the problem. With block 6 I think it has map cooling which just stays blank, the flaps are all on one block and so on.

I'll see if I can get it to work later.

Sent from my VTR-L09 using Tapatalk

 

This all the measuring blocks you can see under hvac, on engine blocks 100 to 150 show no readings on anything. Tonight when testing the Compressor wouldn't permanently engage like it has been it would go on for a moment like trying to start, then stop again. Outside temp was reading 12c feels a bit warmer to me.

Sent from my VTR-L09 using Tapatalk

 

Yeah it doesn't look quite like that, I see that picture is from version 11.11.4, mine like 19.1.3 or something, I have found they have changed a load of stuff, at least it seems as I been using vcds for about 10 years or so.

No, it is the same in every version, I even went back all the way to 2001 to check its first version using web archive:

https://web.archive.org/web/20010422013002/http://ross-tech.com/vag-com/tour/m-blocks.html

I think you have the wrong program if it does not look like that. You can look at current ross-tech homepage also...still same...:

https://www.ross-tech.com/vag-com/

So... if your VCDS looks different, can you take a screenshot and post here? I am curious really what you may be looking at!

 

The only difference is that your climatronic is different than my random internet screenshot so groups have different data.

According to your output the shut-off code is 0.0 which means compressor is on. Also idle speed increase is on pointing to compressor being on. But clutch voltage is empty and you are telling that it did not engage clutch? If it was always 0 but your clutch was not engaging, there may be a fault in the clutch or the relay/circuit providing power to the clutch.

Also your coolant temperature seems to be -99C and for some reason auxilary heater is on (if you have one?). If I remember correctly I see the same temperature as engine measurement block coolant temperature. Do you see correct coolant temperature in your engine measurement blocks?

I can check my climatronic blocks and compare but I have a feeling they will be different than your vehicle. I will let you know...

 

Yeah I thought that temperature and aux heater thing was a bit weird, I am not aware of any aux heater unit, normally they are webasto/eberspacher, I know what they look like and I dont have one of those anywhere in the engine bay I can see!

I had been in the engine and the coolant measurement in those measuring blocks was at one stage showing 96c and I was surprised the fans hadnt triggered, but then I think a minute or 2 later and they did. So it looks like the main coolant measurement is ok.

With The compressor clutch operation: Initially it didnt work, it would come on a bit then go off then come on and go off, like it was trying but didnt like it. Then after replacing the pressure sensor on the bulkhead it seemed to start working.

Lastnight it was working and I changed the longitudinal acceleration sensor (as I am having issues with that bringing the ABS ESP lights on the dash intermittently) for a tested second hand unit which cured my lights/fault codes (once cleared and was fine today), at one stage though the lights came back on and it sounded a bit like the compressor was struggling. Today it was fine until about 5pm, when the heavens opened and it absolutely pissed it down, I got home dashed inside and waited for the rain to stop, took the laptop outside and tried the AC again and this time the clutch was going on and off like before rather than continually running, which at the same time my ESP/ABS lights came back with a fault of 'implausible signal'. I ran the self diagnostic on the Climatronic and it came back with '04FA 00' which is the recerc flap servo motor and '0318 00' which is the AC pressure switch. Now I presume that refers to the switch on the bulkhead?

I am starting to wonder if there is an electrical fault somewhere, but its trying to work out exactly what it is and possibly if its more than one (like the AC is mostly fine, but wont run because the fans done run on low)

I have got a bentley manual with all the proper wiring diagrams in it, so I might have a look through that, could be a bad power supply somewhere thats causing more than one fault, or it could just be I have a ton of broken parts to fix!

 

I checked values from my hvac. They are same as yours (temperature and aux heater stuff included!). The difference is that my compressor clutch engages and evaporator temperature goes down to 4C

I also have -99C, apparently it is not connected as the car has no auxiliary heater. I now remember that I was looking coolant temperature in instrument cluster which was same as in engine.

In engine measurement blocks I only have 137 and https://www.ross-tech.com/vag-com/m_blocks/130-137.html

2nd field turns to ON when clutch engages. 3rd field was showing 6.3bar when it was idle and after clutch engaged it went to 10bar then back to 9bar. Not sure if the values make any sense or correct even...

You should be able to run output test in engine module to activate fans. I forgot to check that on my vehicle but I know my fans come on at low speed when clutch engages.

Here is a related thread:

https://forums.ross-tech.com/showthread.php?1492-How-to-test-Radiator-Fan-Control-Modle-or-relay-with-VCDS-Lite-audi-a4-b6

and this:

https://forums.ross-tech.com/showthread.php?633-Tis%92-the-HVAC-Season

I don't know what else can help you...this is the end of line for me

 

I think you should perhaps first figure out why your fans do not come on. Because if your J293 is faulty then it may effect clutch and other stuff also. We know fans should come on when your clutch engages, and your fans are working (for cooling coolant). Also according to the following diagram, the clutch is controlled by J293 so it knows AC is ON so it should put the fans to speed 1 but apparently it doesn't.

See: https://f01.justanswer.com/vwtech0405/94b7f1f2-a272-482b-9228-fb57ed3d95a0_J293-a4_fancontrol_module.pdf

Maybe you should consider changing it? or first check fuse S225 ? also check G65 is functioning properly.

I am starting to wonder if there is an electrical fault somewhere, but its trying to work out exactly what it is and possibly if its more than one (like the AC is mostly fine, but wont run because the fans done run on low)

I have got a bentley manual with all the proper wiring diagrams in it, so I might have a look through that, could be a bad power supply somewhere thats causing more than one fault, or it could just be I have a ton of broken parts to fix!

Your recirculation flap servo gear is probably cracked. Mine was: http://evren-yurtesen.blogspot.com/2017/07/golf-mk4-variant-v68-temperature-flap.html

It is the F129/G65. But in my vehicle G65 is NOT connected to climatronic. It is connected to engine controller. Perhaps yours is connected to climatronic. That may be why you don't see anything in engine controller in group 137. But the switch may be good, the fault message can be caused due to your radiator fans not functioning. If the condenser is getting too hot for example.

See: http://wiki.ross-tech.com/wiki/index.php/00792

If yours is the switch type and not the pressure sensor type, I guess you can check using multimeter if it switches on/off during operation.

This may be interesting:

http://www.volkspage.net/technik/ssp/ssp/SSP_208_d2.pdf

If it is a 4pin switch then it may be turning off your clutch

http://workshopmanual.com/files/56/pdf/page-3885.pdf

Switch part between terminals 1 and 2 switches off the A/C clutch -N25- when the system pressure is too high or when there is not enough refrigerant in the system .

Switch part between terminals 3 and 4 switches coolant fan -V7- (via the coolant fan control module -J293-) to the next higher fan speed when system pressures increase.

Switch opens when the pressure is below 1.2 bar and closes again above 2.4 bar (switch point).

Switch opens above 32 bar and closes again below 24 bar (switch point). Switch closes above 16 bar and opens again below 12.5 bar (switch point)

 

Right we are getting somewhere ish.

I did the external resistor fan mod to both my fans, sure enough the then started working when you turn the AC on, however the AC doesnt stay on.

Clutch engages, fans come on clutch disengages after varying amounts of time (normally a few seconds) So I left it 'on' while driving home yesterday hoping it would work as the fans come on, however it just did its intermittent thing. Got home and was checking under the bonnet, it tried briefly but nothing much happened, same story of on and off. So I was fiddling about with the fuse block on top of the battery (which is original but looks like new as my cars a low mileage) and sure enough the clutch engaged and stayed running, so I left it running, and the thing started blowing out cold air in to the cabin - NICE!

Checked the pressure of the system while running, on the lower side of OK, but it was blowing out cold air so should be good.

got in it today at lunch time (a little while ago) it started and then the clutch cycled in and out as it does, wiggled the fuses on top of the battery, no result.

Does anyone know if there are any AC connections near the thermostat housing on the VR6? I am guessing its the same place on most cars, but I think I have a really minor coolant leak in that area (like it gets through a cup full of coolant over about 1500 miles, which definitely drips off the underside of the gearbox) which if the coolant got in to a 'waterproof' connector could maybe cause a bad connection. I have looked but theres alot of cables running under there and I always seem to be looking at it when the engine is hot!

The pressure switch on my car is the 3 pin type, I changed it with a cheap new one off ebay (of which there are tons) might consider swapping back to the original and see if anything changes.

I just get this vibe there is a bad connection somewhere, but its trying to narrow down what!

 

I am not sure how fusebox looks has anything to do with mileage of the car as it won't wear when you drive... I changed battery last year and mine was also as good as new (at 290k km)

I expect it showed nothing from the results of your earlier checks but did you check again with VCDS if there is a compressor shut-off reason?

What I would do next would be checking if the clutch power connector on the compressor to see if it is receiving power. Then check where it is connected and work my way backwards.

You should be able to check group 57 to see if switch is functioning (perhaps... I am not sure...)

https://www.ross-tech.com/vag-com/m_blocks/050-059.html

 

I am not sure how fusebox looks has anything to do with mileage of the car as it won't wear when you drive... I changed battery last year and mine was also as good as new (at 290k km)

I expect it showed nothing from the results of your earlier checks but did you check again with VCDS if there is a compressor shut-off reason?

What I would do next would be checking if the clutch power connector on the compressor to see if it is receiving power. Then check where it is connected and work my way backwards.

You should be able to check group 57 to see if switch is functioning (perhaps... I am not sure...)

https://www.ross-tech.com/vag-com/m_blocks/050-059.html

I just meant that its not some crusty old fuse box on a high mileage poorly looked after car with loads of corrosion, its clean and like new, even though its 2001 (but only has about 74k on the clock and was garaged for half its life)

Power to the compressor, its certainly getting it as the compressor engages, I was under it the other night and spotted the connector directly on it, but I'll have to have another look. Annoyingly it was working for a while lastnight before I switched off the car (eg running for 10 minutes with the compressor on for the whole duration making the car nice and cold) Then today, back to intermittent Got home and while driving through our estate I think it did come back on for a small fixed duration as the air coming out the vents started to get cold, then I parked up and it went back to intermittent.

The other feature I have noticed is while on the motorway the air doesnt cool at all, suggesting the compressor doesnt cut in and out, even at low speeds it doesnt do it, it only seems to clonk in on idle.

Hopefully I'll get to look at it over the weekend, I'm supposed to be retrofitting Cruise control and a multifunction steering wheel, so why not take everything to bits!