Strange aircon issue

[GP801]

2005 R171 SLK with full climate control. Looking for some pointers with an odd aircon issue. The car intermittently steams up every so often during a journey. It can be fine for 1 hour or more and then suddenly the inside of the glass is coated in moisture. No discernible change in weather. It can be in the rain or sunshine when this happens.The aircon seems to get cold ok. Its left in auto mode all the time. Switching off the aircon seems to sort it out and it quickly goes back to normal until the next time. If you leave the aircon on it just gets worse. Pollen filter changed <3000 miles ago. Could this just be low gas? I suspect a problem with some control unit or sensors but really pretty clueless with this. It is booked in to be looked at soon but I would appreciate some guidance as to what its likely to be. Many thanks

 

[GP801]

Just a quick update for those that may be interested. It was just a lack of gas. Apparently 100g was missing. No leak. Just time it seems. All back to normal now.

 

[b1g1an]

Glad you're sorted but gas doesn't have the power of teleportation, you've got a slow leak

 

[GP801]

Its never been touched before in 9 years. They claim to have tested for leaks and say they are certain its ok. Time will tell. It was done by MB Gatwick from at their new premises.

 

[Lyserman]

Unfortunately time is money and a proper leak test on any refrigeration system takes hours. They will have pulled a quick vacuum and if it did not immediately rise then they assume it is leak tight.
Slow leaks are exactly that, slow, and can take months for the gas to escape.
Just keep an eye on it by checking the outlet temperature whilst it is full now and if the temp rises later then the gas charge is disappearing into the atmosphere.

 

[Cigano]

had a similar thing on a cls i was driving...cost me £100

 

[GP801]

Another update. Cured it is not. It has started randomly misting up again. Can be just driving along with warm engine and interior when suddenly everything mists up. Certainly seems to be moisture in the system as the water on the windows starts nearest the vent. Its been back to the dealer today and fortunately it was doing it when I arrived so at least they know its not just me. Despite this they can find nothing that is faulty. No damp in the car. Evaporator working. Cools perfectly. They are keeping it a bit longer to investigate further but I would appreciate any suggestions. It has full climate control if thats relevant. My thought is something to do with the control system but I really dont know.

 

[joecash]

is the ac drain pipe clear? in other words does water run on to the floor beneath the car? if no water its blocked and will need clearing

 

[GP801]

The drain is fine they say. Always a little puddle on the floor, They seem stumped but are going to carry on looking. It reminds me of our old 203 which steamed up because it kept going into recirculation mode in error. I have suggested this to them but they seem to think its not this.

 

[GP801]

I know its been a while but here is a quick update. We lived with this happening repeatedly over the winter. It went for a service about 6 weeks ago and I asked them to have another look. This time they found a fault code relating to the compressor intermittently stopping. No indications as to why. However code reset and tempting fate I know but so far the problem has not reappeared. Expect it will at some point but at least we have something to go on.

 

[Walpole]

Hi, just wondering if you have progressed with this issue? Is it resolved?

I have exactly the same problem and have lived with it for three years. Hughes in Beaconsfield have looked at it but to no avail. Appears to happen most often in damp or wet weather.

My work-around is to switch repeatedly on and off but not overly successful.

In winter its quite dangerous - as the light fades and the windscreen mists up - you don't realise how bad it is until you are driving blind! I really need to get it fixed now.

Thanks.

 

[E55BOF]

If Hughes haven't been able to find any codes, it may not be a control problem. Try a call to the chap at Vanchilla in Maidenhead - he really knows his onions where vehicle air conditioning is concerned. Tell him what the problem is; if he doesn't think he can help, he'll say so rather than string you along for the work. He's always busy.

 

[GP801]

Hi, just wondering if you have progressed with this issue? Is it resolved?

I have exactly the same problem and have lived with it for three years. Hughes in Beaconsfield have looked at it but to no avail. Appears to happen most often in damp or wet weather.

My work-around is to switch repeatedly on and off but not overly successful.

In winter its quite dangerous - as the light fades and the windscreen mists up - you don't realise how bad it is until you are driving blind! I really need to get it fixed now.

Thanks.

So far it has behaved perfectly. No doubt it will recur at some point but you never know.

 

[Walpole]

Thanks for the update guys - hope it all remains good.
I'll give the guy in Maidenhead a call to check it out.

Thanks.

 

[v8dve]

Can you guys check that it's not just occasionally switching from 100% fresh air to recirculated when it starts to steam up...

Just a thought