Golf MK5 no cold air conditioning

Hi,

Today I started the car and a squishing noise (from the serpentine belt) was audible and the AC was not working.

The refrigerant pressure is around 6/7 bar at an ambient temperature of 25/30ºC, so, I assume that the circuit has the correct amount of gas.

When, I start the car and activate the AC button, the shut-off code is "0", so, I assume the AC is engaging, right?

Also, the compressor rotation at idle is 900rpm and increases when throttle is applied, so, the serpentine belt is not slipping and the clutch is engaged, right?

No errors on the module.

What could it be?

Thanks.

Faulty compressor valve, expansion valve or blend door for evaporator?

I'm pretty sure the compressor RPM is just derived from engine RPM - there is no speed sensor, at least on my cars - Mine has the wires to the control valve only, but still reports a compressor speed.

Depending on the model, it's likely there is no clutch on the compressor, as it uses a variable displacement compressor, with the control valve that Jack mentions. Both mine have Climatronic, but I suspect climatic has variable too - the really basic AC may be a clutched system? I don't know.

If the "break-away" part of the compressor is faulty (usually because the compressor has seized), then the inside of the compressor won't be turning - I believe the bolt inside the centre of the pulley won't be turning?

The Control valve Jack mentioned is a common fault on the MK5 platform - I've had to replace both on my Tourans. I used valves from RKX tech, via ebay, but they do have a website.

If it's the control valve, you may find the AC intermittent, or extremely variable - sometimes cold, sometimes hot feeling, just all over the place (both mine were like that, anyway). Neither had a fault code logged related to that.

There is also a flap alignment procedure that you can do in VCDS (or the "secret" climatronic shortcut). VCDS will report the flap position, though it could be a disconnection from the actuator too, possibly.

Can always be disassembled to inspect the beak key and if resourceful you can repair the key because I have found it breaks with insufficient reason too.
Such a fucking stupid design!

If slightly over charged or if PSI comes up on really hot day the key breaks & when you really need AC!

I recommend running lower on freon and an auxiliary radiator fan on condenser to make cooler and more fuel efficient!

Doing this permits the system to permit a bit more lubricant & the valve that always fails to also operate with longer life!

Hi Jack. Hi Allan,

I believe you are right. This compressor has variable displacement compressor and not a clutch.

I will look if the centre bolt of the pulley is turning and report back.

But I think the squishing noise was the belt slipping due to a seized compressor.

Confirmed! The centre bolt of the pulley is not spinning.

Vasco Ferraz said:

Confirmed! The centre bolt of the pulley is not spinning.

Click to expand...

System flush and new components required....

golfi_vend said:

System flush and new components required....

Click to expand...

Thanks

As suspected, this is out of my league... that is, I don't know the procedures to remove, store and recycle the gas.

Also, I don't have professional equipment to refill it.

So, this doesn't worth to risk to replace the compressor and the dryer and after sending the car for a refill the shop report back a leak due to my amateur job.

Early mk5 had issues with internally failing compressors that made mess with metal debree.

Shop would need to flush piping with drilled expansion valve(or adapter), without compressor and condenser. Install new compressor, condenser(with drier), expansion valve and match old and new oil quantity in system.

And some other small things that come with experience.

I am again back on the game.

Today I went to a "Bosch Car Service" for a diagnose and the problem is the clutch plate.



The inside of the spline in the clutch plate is worn out and does not make contact with the spline of the compressor shaft.

The problem is that not even Bosch or the dealer has this clutch plate or even the full pulley available for purchase.

Guess what, the only option is a new compressor, which implies replacing an original and full working compressor with a cheap one, plus 3 or 4 hours of labour, plus a recharge, instead of a simple clutch plate.

As I did a previous research I knew before hand that the clutch plate or the full pulley is available for purchase on online stores.

The plate clutch costs 15€ plus 10€ of shipping, has 4 bolts, doesn't even need to remove the passenger front wheel (just the splash guard).

I paid 25€ for the diagnose and thanked their diagnostic

I hope to replace the clutch plate, not this, but next weekend.

Mk5 uses variable displacement compressor. There isn't clutch plate, compressor is always running, even when shut off.

There is a reason why it is broken....

golfi_vend said:

Mk5 uses variable displacement compressor. There isn't clutch plate, compressor is always running, even when shut off.

There is a reason why it is broken....

Click to expand...

Hi,

I did not understand what you mean.

Are you saying that the plate (being a clutch or not) got the spline worned because a seized compressor?

Bosch Car Service told me that the compressor is good. Also, the system has the correct amount of gas.

So, are you saying that replacing that part won't solve the problem because you suspect that the compressor shaft is broken or the compressor seized?

golfi_vend said:

Mk5 uses variable displacement compressor. There isn't clutch plate, compressor is always running, even when shut off.

There is a reason why it is broken....

Click to expand...

Check this video. This is what I suspect that happened to my compressor.

https://youtu.be/kkJtjgLTa8M

Read the description to understand why this problem happens and why now it is possible to repair without the need of replacing the compressor.

Just to report that I replaced that plate and the AC is working. I drove 60km without any issue or strange noises.

500€ job versus 15€ for the part, 10€ for the shipping and those first 25€ for the Bosch Car Service tell me that they can't only replace the disk... just the full compressor.

I am a cheap scavenger.
I just mig weld and cut new splines. No pulley or real cost & no freight but that's the difference between parts changers or skilled & with ability to improvise their time.
Most can't do what I aforementioned but they should learn.
I commend you for posting this easy solution.
Additionally I have drilled rivets and sourced center hub.
Desperate quick and dirty to get AC I have drilled the hole of old hub and then mig welded the plate to shaft in place in car and everyone I did is still working!
I cheated with heat transfer cream!

Hi Jack,

I am almost sure that the splines of that plate are made of aluminium and the compressor shaft is made of steel, so, I think that plate acts as a fuse in case of the compressor slows down because of an additional friction inside the compressor (I know that if an additional friction occurs the compressor is not in good shape).

But instead of wearing down only the splines of the plate, the shaft might also get rounded (wear out) and the labour of reconditioning the compressor shaft would be higher and probably its insides would be totalled.

So, in my opinion, the best approach is to replace that plate instead of repairing, permanently rivet or solder that plate into the shaft.

Also, as I do not have those skills or equipment, 15€ for the part and 10€ for the shipping, doesn't worth the money and time to out-source such task.

That is correct but if you know how to mig you can fill the hole and the steel shaft cuts new splines and you just install a bolt.

In other cases I installed a steel center hub from older compressor clutches too!