Air con not cold - where/what to check?

[LPH]

Last year I had the air-con in my 2007 V8V re-gassed as it was not blowing cold. Used a local mobile specialist who is very good. He did a prosper full pressure test etc and it all checked out. I was talking to him as he did it so know what he did. He left it for about 30 mins on the pressure check and nothing leaked.

Was working great after he left. 12 months on and it's not cold again.

What the the usual suspects for leaks in the system. AFAIK there is dye in the system that he added and can't see anything obvious.

Cheers

[Jon39]

I have exactly the same with my DD.

The only comment I can make in reference to your question, is I think an ultra violet light is needed, to see any of the diagnostic dye which might be leaking from the system.

[abanks]

Most common cause of leaks is a small hole in the condenser as it is prone to stone damage. The dye test should find it. Or it could be the AC Compressor is failing.

[LPH]

Excellent that sound expensive!

Thanks for the replies.

I have had a leak before in a daily driver and I could see that die without the UV light. It was much brighter with the UV but noticeable without.

[Virage orange]

I had this problem on my vantage. After changing the condenser and it still leaked away it was finally traced to perished O rings on the pipes to the compressor. If it is your condenser I have one which I think is ok from a 2008 vantage roadster.

[8Speed]

Try cleaning the aircon radiator which may have become blocked with bugs etc.
Just need to remove slam panel & grille to spray, degrease, etc.

[woodsypedia]

Sadly I went through this pain on my V12V. Car went to works 3 times to resolve. Turned out to be a faulty seal near the recharge valve. Sadly, it took a lot of work to find.

[Cold]

Our cars are a similar vintage. I replaced my condenser a couple of years ago due to leaks from the crunchy bits and it would be the first thing to check on any car of this age.

Not a huge job and DIY-able if you're ok holding a spanner but the degas/refill will need a specialist. It is always a good idea to replace the receiver drier as a matter of course if you open/dismantle the a/c system.

[RMDB9]

When my aircon is on, i sometimes have cold and warm air in the cabin, warm blowing from somewhere behind the steering wheel. also the temperature setting when on "auto" needs to be set much lower than the actual outside temperature.
ideasß

[F1NDW]

You need to keep using your AC as a dehumidifier over the winter to keep the compressor seals lubricated and stop them leaking.

[V8PYB]

F1NDW is correct, there is a carbon seal on the compressor which is lubricated by the compressor oil. If it dries out it leaks and when it gets lubricated it stops leaking, but the system will need topping up with refrigerant. The recommendation is that the AC is run on a regular basis throughout the year. I never turn my AC off as the cost of running doesn’t make that much difference to 17mpg anyway. Ultra violet leak checking only works if dye has been put into the system, not something I recommend as it can cause problems if not done correctly. The most up to date leak testing devices are ultrasonic, effectively listening for the noise of refrigerant gas escaping from the system. Holes in condensers are usually large enough for the leak to be identified very quickly when the system is put under pressure.

[8Tech]

V8PYB said:

F1NDW is correct, there is a carbon seal on the compressor which is lubricated by the compressor oil. If it dries out it leaks and when it gets lubricated it stops leaking, but the system will need topping up with refrigerant. The recommendation is that the AC is run on a regular basis throughout the year. I never turn my AC off as the cost of running doesn’t make that much difference to 17mpg anyway. Ultra violet leak checking only works if dye has been put into the system, not something I recommend as it can cause problems if not done correctly. The most up to date leak testing devices are ultrasonic, effectively listening for the noise of refrigerant gas escaping from the system. Holes in condensers are usually large enough for the leak to be identified very quickly when the system is put under pressure.

+1 on everything above. Always keep the AC switched-on, even in winter to keep the compressor lubricated as it will not cool the air if you have the temp set higher that outside temp anyway.

Usually the condenser though, easily traced with the proper AC "sniffer" tools.

[Astontony]

Hi
Do you have ambient temperature sensors on the db7? On my db9 my sensor was showing 32c when it was actually 23c so the air worked overtime. Maybe yours is the opposite which is quite possible and your air actually doesn't work because it isnt actuated as the temperature is registering incorrectly.
Changed my ambient temp switch and it took 20 mins all up and now it says 23c
This may be a cause of your problem.

[V8LM]

Same happened in my SVR. Checked and re-gassed in October. Stopped working by February. Turned out to be a hairline crack in the evaporator.

[EVR]

F1NDW said:

You need to keep using your AC as a dehumidifier over the winter to keep the compressor seals lubricated and stop them leaking.

This is good advice. I use to just switch on normal hot air in winter.