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Joined: Apr 23 2019
Posts: 79

I had mine done recently at ATS. The machine recovered no oil (as in, there was nothing there), and then they added 5g of PAG oil and 5g of UV/ oil mix (along with 1250 of R134a). Those figures came from whichever database ATS use - either way they're not just putting back the same amount they recovered, so I wouldn't mess around, just take it to a centre that has the right reference data. Groupon are doing 36% off at ATS currently...

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Joined: Nov 16 2016
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But surely just because a machine recovers no oil it doesn't necessarily mean there was none in there? The oil would have to evaporate under vacuum conditions for the machine to be able to pull all the old oil out.

My take on the machines is that they are there to pull old gas out, vacuum test (which will also boil off water) and push new gas in... but they have to be able to cope with some oil. No easy way of getting old oil out? It wouldn't be much good just sticking X amount of new oil in the system on every fill or eventually after enough refills the AC system would contain just oil and no refrigerant.

Analogy - Could remove an engine's oil filler cap and shove a vacuum cleaner pipe in the hole (maybe as part of some PCV valve test or something), would expect the vacuum cleaner to pull some oil out but what force is the vacuum cleaner providing that could possibly get all the oil out of the engine including from the sump?

Think I'm going to just have to guestimate it... I will have added some extra oil when using one of those Halfords DIY regassing kits (some oil in those bottles), question is was there the correct amount of oil in the system before I used the Halfords kit considering my system had a leak at the lowest point of the system and some of the AC pipes are a metre or so above the lowest point.

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Joined: Jul 12 2016
Posts: 857

romanrob wrote:

I had mine done recently at ATS. The machine recovered no oil (as in, there was nothing there), and then they added 5g of PAG oil and 5g of UV/ oil mix (along with 1250 of R134a). Those figures came from whichever database ATS use - either way they're not just putting back the same amount they recovered, so I wouldn't mess around, just take it to a centre that has the right reference data. Groupon are doing 36% off at ATS currently...

I've found that the machines often have the wrong (lower) amount gas. The sticker/plate on the front of the car says 1380g I think.

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Joined: Jan 05 2016
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Depends on year - if its GEMS, its 1250, Bosch/Thor takes 1380 :)

Get a print out if you can if its done with a machine, which should prove how much has gone in. Unless they've been crafty and snuck a weight on the bottle scales during filling... I wouldn't put it past some.

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Joined: Apr 23 2019
Posts: 79

lpgc - fair comment, zero recovery doesn't mean zero oil - although the tech's reaction at seeing zero oil recovery suggested he was used to seeing at least _something _come out as an oil fraction - and the machine print out specifically records recovered oil. Still seems you're best off having a shop add the oil through the port, which is, as you point out at the top of the system - although if you were to replace the compressor they recommend adding oil direct to the unit before reconnecting. Sloth seems the expert on air con so I defer to him though.

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Joined: Jul 12 2016
Posts: 857

Sloth wrote:

Depends on year - if its GEMS, its 1250, Bosch/Thor takes 1380 :)

Get a print out if you can if its done with a machine, which should prove how much has gone in. Unless they've been crafty and snuck a weight on the bottle scales during filling... I wouldn't put it past some.

Ah, I didn't realise there was a difference based on year. The machine in our workshop on lists 1250 for all models of P38. When I had it done I had to point out the sticker and they had to manually set up the amounts instead of letting the machine figure it out.

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Joined: Nov 16 2016
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RutlandRover wrote:

The machine in our workshop on lists 1250 for all models of P38. When I had it done I had to point out the sticker and they had to manually set up the amounts instead of letting the machine figure it out.

I always check the machine/firm has the same weight dialled in as the sticker says on the car, a lot of my cars would have been under-filled by quite a percentage if I hadn't including Grand Voyagers by about 300.

Even then I wonder if the shop's machine accurately measures the amount of stuff it puts in - Sometimes after such shop re-gas I've gone straight back to base and tested using Halford's DIY kit, it's only a pressure gauge but pressure is supposed to stay in the green with AC blowing full and engine at idle, often the pressure gauge has gone below green and I've put a bit more in from DIY kit to make up for it - and the AC has worked better after I put the extra in.

I don't really trust Charlie Brown / Quickfit type places for AC, they're hardly experts at AC. But I use them because they are cheap compared to a 'proper' AC specialist who should really know what they're doing. It's like gimme the goods, never mind about your lack of expertise I'll take it from here...