Aircon Problem

[sjoyce666]

I have a problem with the aircon in my 03 TDi 130 Alhambra

With the engine running and aircon switched on it will blow out cold air for around 15 seconds, after this is blows out warm air getting hotter

I have had the system regassed this morning at Kwik Fit. There was no charge as they couldn't get it working for more than 15 seconds so nothing lost but not the quick easy fix I was hoping for. I checked with the technician and the system was empty on arrival and they put in 700g of refrigerant as I have front climate control only

The technician mentioned that it could be a weak compressor at fault as at idle it puts out cold air but when revved it blows out hot air as if the compressor cannot keep up. I left the car running in the car park and even at idle after 15 seconds or so it started to blow out gradually warming air until it was so hot I had to turn the aircon off and open the windows. The system losing all of its gas would suggest a leak but it was leak and pressure tested without any problems. Could the gas escape through prolonged on/off if the compressor is at fault?

I have searched previous topics on the forum regarding aircon and compressors and it looks like the compressor or the pulley could well be at fault. The compressor is kicking in as when the aircon is on the revs are fluctuating slightly due to the increased load

I will get VCDS Lite setup on my laptop tonight and scan for codes. Could the problem be with a code that is logged and just needs clearing? Could it be the pressure switch or is it likely to be the compressor? Any fuses I could try replacing? It is a strange fault in that it does work but only for a short amount of time. Any other suggestions welcome

Thanks,

Scott

[Mirez]

If the system can't get rid of the hot air then it obviously won't cool, so firstly check the radiators are free from debris and secondly see what the fan on the back of them is doing? It should come on as soon as the A/C in turned on.

[insanitybeard]

I'm curious by what you mean when you say you get chilled air for 15 seconds or so and then it gets progressively warmer, do you mean that the air coming out then becomes heated (i.e, warmer than the ambient air temperature) or just is no longer chilled?

[sjoyce666]

I'm curious by what you mean when you say you get chilled air for 15 seconds or so and then it gets progressively warmer, do you mean that the air coming out then becomes heated (i.e, warmer than the ambient air temperature) or just is no longer chilled?

Hard to tell as it has been so hot today when I was trying it

The air is chilled to start with and then gets warm/hot

I have hooked up VCDS and there aren't any fault codes in 08-Auto HVAC so looks like the brain side of things is working

I'll have a look at the fans and see whats happening with those

Scott

[sjoyce666]

Fan on the back of the radiator spins up and stays on as expected when aircon set to auto. We had it set to 22 degrees and it blew out cold air for a while. We then set it to LO and it blew out warm air

Having a look through the bottom grill of the front bumper I can see a pipe which seems to be leaking a green fluid. Any ideas what this could be? It is around the bottom of the radiator where I assume the aircon bits are

Scott

[SilverBeast]

Which pipe?

[attach=1]

Silver one on bottom left and silver one on right middle with a black ribbed cover are air con pipes.  The big black "radiator" you can see is the condensor with the black vertical tube on the left hand side with a sloping top contains the drier.  I believe the small radiator is the oil cooler.

They often put green dye in the refridgerant in order to find leaks.  It's usually fluorescent so if you've got a UV light it should "glow".

[sjoyce666]

Circled where I found the leak and attached the image

Looks like the aircon is weeping from the pipe. Is it a case of replacing the pipe? Can it be tightened? Would this cause the problem I am experiencing?

Scott

[SilverBeast]

It depends where it is leaking from. That pipe bolts onto the condenser and has an o ring seal in it. Of you are lucky the o ring has failed (not the pipe) and it can just be replaced, refitted and the system refilled. Whether it would cause your symptoms I don't know enough about it. The pressure switch is on the other end of the pipe so it may have registered as a low pressure when the refridgerant leaked out.

[sjoyce666]

It depends where it is leaking from. That pipe bolts onto the condenser and has an o ring seal in it. Of you are lucky the o ring has failed (not the pipe) and it can just be replaced, refitted and the system refilled. Whether it would cause your symptoms I don't know enough about it. The pressure switch is on the other end of the pipe so it may have registered as a low pressure when the refridgerant leaked out.

Refrigerant was only filled today and there isn't a massive amount of green liquid escaping but I dont know how much green liquid equates to how much gas. There haven't been any faults making the climate panel flash and when scanned with VCDS earlier there weren't any fault codes. The machine also didn't flag any leaks or pressure problems.

[sjoyce666]

Another small update

I had a look at the condensor this morning through the upper grill and it looks like it has been changed in the past as the casing has been cut to give better access to the bolt

Could it be the case that under load the system is sucking in the warm air from the engine bay and the cool air after the compressor and condensor is escaping before it reaches the cabin?

[insanitybeard]

From what I've seen the air con pipe aluminium unions are susceptible to corrosion around the joint where the O-ring on the male part of the joint seals up into the female 'socket', mine had green dye escaping for this exact reason (on a different pipe to yours). However, I think this kind of leakage is fairly slow (over a period of weeks/months for example) and therefore may not be picked up in the short time they either pressure or vacuum test the system before refilling it with gas. I also don't think it's related to your fault, eventually if it is leaking it will cause the system to shut down when the gas leaks to such an extent there isn't enough left for the system to operate properly or operate the pressure switch, but it won't be the cause of the problem now, if the system is working for a short period of time.

I think you need to clarify if, when the system blows cold (chilled) air briefly and then warms up, if the warmer air coming out is just at ambient air temperature or if it is actually warm air from the heater radiators in the blower boxes- this would imply that a heater flap or actuator was defective in the heater box but would also occur when the air con was switched off. Also, if this was hapenning it shouldn't occur when the engine has just been started from cold before the engine/ coolant has warmed up.

[SilverBeast]

Have you tested the temperature of the two pipes that the fill connections are on after the system has been running for 10-15min?

One should be hot, the other cold with condensation on it in this weather.  That should tell you if the refridgerant is circulating and the compressor doing it's job.  You can do this (carefully!) with your hand, as it isn't a subtle temperature difference on either pipe.

[Chrispb]

While any leaks would need sorting and be warned the pipes that run through the O/S wheel arch are quite well hidden they also tend to leak under the support clips, the green dye usually makes this easier to see but not so visible as around the condenser.

As said one pipe will be quite hot and the other cold with water droplets if it's working, the clutch on the compressor should be engaged continuous on the diesel versions also the radiator cooling fans.

Personally speaking kwik fit are only any good if your system doesn't have any issues but don't have a clue when there's a problem.
If I was you I would get a second opinion from a mobile aircon specialist who can check the running pressures or a possibly blocked expansion valve, this is situated on the bulkhead before the pipes go through into the heater unit inside the car.

[sjoyce666]

Been out for a drive and both pipes are hot

One is hotter than the other but one is not cold. I would say the cooler of the two pipes is about as warm as the air coming out of the vents. The fan on the back of the radiator spins up as it should do when aircon is on

I am aware Kwik Fit are not going to be able to diagnose the exact problem. I went to them because they do not charge you if a leak is found or if they cannot get the aircon colder. I was hoping all I was going to require was a regas. Obviously this is not the case hence this post on what the possible problems could be

[insanitybeard]

For some reason Chris I thought the expansion valve was that canister shaped unit welded into the pipe on the offside near the condenser just before the pipe dissapears under the front panel- is that not the case?

[Chrispb]

Sorry had to put this video on, rather amusing and makes it look easy.

https://www.youtube.com/watch?v=RkKry31lk1E

[steve329]

Makes it less than 4mins to change expansion valve - might pop out and do mine :-/ lol