Air Con - P38

Having recently bought a 2000 4.0HSE I noticed the AC wasn't working so before getting it the garage found the Condenser was goosed. Simple, they fitted a new one and re-gassed the system and home the car came.


After a short time I noticed it wasn't very effective in the damp weather so I gave it the cold screwdriver test i.e stick it in the valve on the low pressure line and - nothing - other than a faint hiss that lasted about half a second. EMPTY.

Went back and told them. Simple fix "we'll check it and see what's wrong" "maybe because we fitted a new condensor it needed more gas than usual" :blabla: (starting to wonder if he knew what he was doing now!). Re-filled with a leak dye too and got it back. Got home, no AC/ pump not clicking on and off, phoned them back and was told, "we used a whole tin of gas". I asked what oil they had used and this got an "ugh?" in response. (Confirmed they don't know what they are doing.)

Had a look under the bonnet and found the leak dye was spilled all over the inner wing. He told me he'd spilled it, but just left it. Seemed to question my knowledge when I asked if the system had been evacuated and held on vacuum for a period and a whether a measured amount of oil and gas was put in. Again he repeated that he had used a whole tin. (Surely not these DIY efforts!!!) I pressed the low pressure valve again and was met with a squirt of warm green dye and not the usual stale R134 smell - you've guessed it - normal air!

My question is (at last) how long should this system be held on vacuum before re-filling? I know it needs about 1400 g of gas but what is the oil type and quantity? Handy to provide this info when he gets an "expert" to look at it on Monday.

Specialist aircon workshops and some countrywide franchises have all-in-one machines that evacuate all the remaining gas before leak testing and refilling...costs about £70. No "tins" of gas - that sounds suspiciously DIY!!! Use a specialist or a franchise outlet where someone has been trained to use the machine! Sounds like a leak somewhere - shouldn't be rocket science to repair!

rangiegal said:

Specialist aircon workshops and some countrywide franchises have all-in-one machines that evacuate all the remaining gas before leak testing and refilling...costs about £70. No "tins" of gas - that sounds suspiciously DIY!!! Use a specialist or a franchise outlet where someone has been trained to use the machine! Sounds like a leak somewhere - shouldn't be rocket science to repair!

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Yep, £70 for a air con service and refill is about ball park. Just had my Golf done recently.

Thanks, I had AC with my Volvo, Jaguar and with the other P38 which we still have, just thought I'd have a despairing rant about the cruddish explanation I was offered today. There is pressure in the system now, its just that he has squirted gas into the air that's already in the pipework which is causing all sorts of confusion with the pump. I am assured they will have someone with a machine do it on Monday. (Maybe stick around and watch! Just to be safe.)

Normally, the system is vaccumed down and left for around 10 mins to see if there are signs of leakage.
Oil & refrigerant quantities are:

V8 Gems 150cc Sanden SP10 oil, 1250g R134a refrigerant

V8 Thor 180cc Nippon Denso.ND-OIL8 , 1380g R134a

Diesels 140cc ND-OIL8 1100g R134a

If the condenser is replaced, the system should be topped up with around 40cc of oil.

No doubts there are equivalent alternatives to the above oil specs.

Forgot to add....If a leak is suspected, but initially difficult to find, the system should be emptied and regassed with Nitrogen (Inert gas and far cheaper) + leak detector dye. Leave this in the system for about a week and recheck for dye traces and loss of pressure.

Thanks, you would think they'd be the same throughout the range however it's a P38 after all. I don't think there's a leak as there is pressure being held so we'll see how the vacuum test goes. At least I know which oil goes in now.

Update re Air Con. Didn't take car back to supplying garage but to the place I normally use for things I can't manage. Drained 345grammes of gas( about one tin!!!) and however much dye, held on vacuum at 20 mb for about 10 mins then re-filled. He programmed 20ml oil, 5 ml dye and 1380 grammes of gas. The system works fine now with the pump coming on and the interior cooling down but on re-reading this should he have put in about 10 times the oil he did or would there be any residual left despite the evacuation? Wouldn't fancy the pump seizing or the system corroding through lack of oil from the inside out.

There would have been a fair amount retained in the compressor inners, You should be o.k. now.

Thanks for the replies and info. Just about froze on the way home that day, making sure it was working!