Air Conditioning Fault - Advice Please

[TonyC911]

Hi Guys,

Noticed last week that my air con was not cooling at all on my 2012 991.1 2S

When I checked the refrigerant gas, the system was empty. I added some gas and at first no obvious leak, but then I spotted two small dark spots on one of my condensers.

I just collected it from the garage after a major service and they noted the same problem, but said they did not spot any obvious leaks and further investigation would be required.

After a week, a considerable amount of the gas had remained in the system. I replaced the condenser yesterday and re-charged with gas again, but no change in temp. There is now a noticeable hissing type noise coming from behind the central air vents when I switch on the air con. The system is still holding its charge when I checked it this morning :?

Anyone experienced similar or got some advice on troubleshooting? I was thinking of changing the dessicator next?

 

[C4Silver]

Looks like its wet underneath, dye and PAG Oil resting on the surface that's leaked from the condensers, If you have access to an UV light that should show up any leak as the Dye has a trace in it.

 

[deMort]

The damp spot on the condenser would at best be a very slow leak at best ...

The system was empty or thereabouts .. you have regassed it with i assume 900 grams and it still doesn't blow cold ?

In this case with the correct amount of gas then a sensor such as interior temp is reading incorrect .. in other words its seeing a temp of some sensor that it will not turn on the A/C... a/c doesn't work below 6 degrees i think as an example .

This is strange in that it would appear you have 2 seperate faults .

A hissing noise is a common sound on a system with lower than normal a/c gas .. it's a noise that will stop if you turn off the A/C .

This would indicate the system is working but at a reduced rate due to low gas .. a leak .

Common faults .. well ones i've seen are the pipes to the o/s/f of the battery .. there was a recall on these pipes years back and the the pipes behind the o/s/f wheel arch liner .. the dryer is there .

You basically look for an oily damp patch .. similar to the condenser image but more obvious .

If dye has been added then its a bright green residue .

A garage would pressure test the system with nitrogen to find the leak .

 

[nickyg63]

often a hissing sounds is from the TXV (thermal expansion valve) when the refrigerant is low. As Demort has said.

This is a good sign in that the refrigerant is being moved around the system, so i wouldn't say that any components aren't working. its high enough pressure for the pressure switch to let the compressor still work, if you have access to a "sniffer" you can try to track down where the refrigerant is leaking.

if the noise has occurred just after the new condenser like described, my hunch is low on refrigerant and the system will work more efficiently after another recharge.

 

[TonyC911]

Thanks guys for your ideas and thoughts!

I have ordered a new dryer/receiver. Earlier in the year I did notice a bad smell in the cabin with the air con on, which is most likely where the desiccant has become saturated and become stagnant.

I'll replace the unit at the weekend re-charge it and use some soapy water to see if I can identify any leaks from the pipework. If that doesn't work I think I'll try and find a mobile air con tech, to visit.

 

[TonyC911]

One thing that is bugging me about this fault is that I did not notice any change in engine revs when switching the A/C on, which on other cars I have owned suggests the compressor clutch is not engaging :dont know:

Any thoughts appreciated!

 

[nickyg63]

Thanks guys for your ideas and thoughts!

I have ordered a new dryer/receiver. Earlier in the year I did notice a bad smell in the cabin with the air con on, which is most likely where the desiccant has become saturated and become stagnant.

I'll replace the unit at the weekend re-charge it and use some soapy water to see if I can identify any leaks from the pipework. If that doesn't work I think I'll try and find a mobile air con tech, to visit.

The smell most likely is bacteria on the evaporator, you can clean this with a interior bomb.

The dryer takes water from the refrigerant, so swapping this is good preventative maintenance. i would recommend vacuuming the system to boil away any moisture to prolong the life of your dryer.

best of luck

 

[TonyC911]

Had some good news today...

I was struggling to find any leaks in my system, which led to me removing the wheel arch liner and under-trays, but still nothing obvious. Decided to replace the 2nd condenser, just in case, but still no cold air :x

Took the car over to kwik-fit today. The mech was super helpful and ran a long vacuum on the system and thankfully came up with no leaks. After a quick re-charge I now have super cold air! :thumbs:

The mech mentioned that the system required a large amount of refrigerant, compared to other cars, so I suspect my DIY gauge is calibrated for more popular systems and consequently I was not adding enough gas. He also mentioned that UV dye is added to the system with the re-charge, so should be able to identify any leaks in the furture with a UV torch.

 

[MJA911]

That is good news, when demort mentioned 900grams earlier in the thread I though that was a lot compared to other cars, my 986 is 500grams I think. Out of interest, what condensers did you buy? One of mine on the 991 has a damp patch, aircon is cold, but seems like there's a good chance it won't be at some point.

 

[deMort]

986 is 850 grams .

useful site to get an idea on filling quantities ..

https://www.hella.com/techworld/uk/.../Car-refrigerant-oil-filling-quantities-2114/

 

[MJA911]

Ah thanks, must have been daughters Fiat that was 500, had them both done lately, used that site to get the amount for it actually, doh!

 

[TonyC911]

That is good news, when demort mentioned 900grams earlier in the thread I though that was a lot compared to other cars, my 986 is 500grams I think. Out of interest, what condensers did you buy? One of mine on the 991 has a damp patch, aircon is cold, but seems like there's a good chance it won't be at some point.

I used Coolpartsuk on eBay. I've used them before on another car and whilst they are at the cheaper end of the scale, I've not experienced any problems - https://www.ebay.co.uk/itm/274113634262

They are pretty simple to replace, taking the bumper of took me longer! :roll:
It is recommended that you also replace the O-rings when changing any parts, which your friendly OPC can supply :thumbs: