Oil in Air-Con Gas

jcwatrichmond · 13th July 2011, 13:40

I've just talked to a mechanic in a garage that does re-gassing. He reckons that when the gas is extracted, the machine measures the amount of oil that comes out and so they put the same amount back in when re-gassing.
That's fine if the amount in there was correct to start with. I suspect that my air-con is low on oil, even though it was re-gassed by Kwik-Fit twelve months ago, as it whines a bit in use. It doesn't sound like the belt to me. So how do I know that the amount is correct?
When they suck out the gas and oil using a vacuum it won't remove anything like all the oil apparently, but the longer they leave the vacuum on the more should come out. This guy looked up the total amount in a 75 on his computer and came up with the figure of 100ml which surprised him as he expected it to be a lot lower. I've now noticed that in a previous post TC added to the photo of the label above the grill under the bonnet 'Nippon Denso 8 oil, Amount: 110-130ml. This would presumeably amaze him.
Is he a bit switched off or is this all a bit academic? I'm not well up on air-con and I don't want to risk a disaster.

John Wright

eddiemc05 · 13th July 2011, 20:37

Its called pag oil, a machine will take out as much as it can, the same amount wilk go back in as long as the operator has filled the bottle correctly and should introduce another 10 ml or so u can tell the machine how ever much extra u want,

chrissyboy · 13th July 2011, 21:36

our machine has all the cars specs stored so it takes out what is in there and puts back the amount that is supposed to be in the car ...

T-Cut · 13th July 2011, 22:01

The oil is dissolved in the refrigerant when it's liquified. When the refrigerant turns to gas in the low pressure circuit, the oil in that portion stays put on the surfaces of the pipes/compressor inlet etc. Oil will also be carried through in very fine droplets of refrigerant vapour. That's basically how it lubes the compressor. When they empty the aircon system, they'll get as much of the refrigerant out in liquid form they can. The oil comes with it. When all the liquid's out, they'll evacuate the system to get any residual refrigerant and moisture out. Whatever oil is in there at this stage stays in the system because it's not volatile. So, some small amount of oil will remain after they've vacuumed it down for a while. I'd say the weight left will be trivial and is probably ignored. So, when they recharge with refrigerant, they should add the mean volume of the Nippon Denso 8 that's stated on the photo. You should ensure they add this amount, which may not be what 'the computer' says they should add. I guess the specified Nippon oil is the same stuff as is universally added, though I have seen no confirmation of that.

This is the label.

TC

jcwatrichmond · 14th July 2011, 07:19

Thanks for the information. It seems that the garage mechanic that I first mentioned doesn't know too much about it and should be avoided in future. He was only going to add the same amount as had come out plus 5ml, so how much was in there was anyone's guess.

JCW

SD1too · 14th July 2011, 07:45

John,

To be fair to the garage mechanic I think he was just covering himself against being held responsible for any complaints. But I agree that he should be able to determine the correct amount of refrigerant oil. I suspect that many operators have bought an air con. machine to increase their turnover but don't have a great deal of experience in the field.

My real concern would be about Kwik-Fit. Did they add the correct amount, or indeed any oil when they recharged your system? I know that they're cheap, but they're not air con. specialists. Exhausts and tyres are their mainstay. They just added air con. to their list of services to expand the business.

After previous dissatisfaction I've found an excellent self-employed mobile air conditioning chap. He comes to my house so I can see for myself what he's doing. He's not cheap, but is very thorough. It's an option you might like to consider.

Simon.

chrissyboy · 14th July 2011, 09:08

Quote:

Originally Posted by SD1too

John,

To be fair to the garage mechanic I think he was just covering himself against being held responsible for any complaints. But I agree that he should be able to determine the correct amount of refrigerant oil. I suspect that many operators have bought an air con. machine to increase their turnover but don't have a great deal of experience in the field.

My real concern would be about Kwik-Fit. Did they add the correct amount, or indeed any oil when they recharged your system? I know that they're cheap, but they're not air con. specialists. Exhausts and tyres are their mainstay. They just added air con. to their list of services to expand the business.

After previous dissatisfaction I've found an excellent self-employed mobile air conditioning chap. He comes to my house so I can see for myself what he's doing. He's not cheap, but is very thorough. It's an option you might like to consider.

Simon.

we have had 3 months of training proir to buying a machine .,had a car in yesterday where when they put the air con it was as though the heater was on ,the guy had just had it done in quick fit ,instead of them telling the guy he needs that sorted first they just took his money and just tooped up the gas , by the way the problem was ,the hearted only blew hot air even when switching to the blue so cold air should of came out ..when he has done that we will service his air con system ..,
edit ,we have another guy the has joined us for training in air con ,he has been doing it for 5 years as a mobile service ,the other week in our mock test of 15 questions he only 3 right ..how many did i get i hear you ask ... i only got 11,two questions i didnt agree with so got them wrong .main one being retro fitting from f12 to r134a . i found lots of info from companys that say the gas should be filled to only 85/90 % of the original capacity ,so i put that ,it appears its 60% but then to me this is nearly half empty so the air con wouldnt work too well...

jcwatrichmond · 15th July 2011, 07:49

This air-con refilling seems to be a bit of a 'black art'!!

JCW

T-Cut · 15th July 2011, 11:22

Quote:

Originally Posted by chrissyboy

info from companys that say the gas should be filled to only 85/90% of the original capacity - - - it appears its 60% but then to me this is nearly half empty so the air con wouldnt work too well...

Can you explain this because it makes no sense to me at all? The slam panel label clearly states the amount of gas that should be present in the 75/ZT aircon system. When the system is emptied and evacuated as it should be, there will be absolutely no refrigerant left, not even a smidgin. So why would anyone refill the system with only 60% (or indeed 90%) of the original capacity? It is nonsense in my view. Can any aircon expert on here explain this, cos from a physics standpoint it's loony.

TC

James.uk · 15th July 2011, 14:22

From what I have seen, and remember my mech doing --- He messes with the lil panel on top and I think - he tells it what make model the car is..? he then turns it on and leaves it. The machine removes what's in there, then replaces it with the correct amount for the car..

I then get billed for the amount used in the refill, less the amount that was already in there... innit???

It does put both dye and some lubricant into the system..

...

13th July 2011, 13:40	#1
jcwatrichmond Loves to post Rover 75 1.8T 2003 Club SE Join Date: Jan 2009 Location: Solihull, Posts: 370 Thanks: 0 Thanked 0 Times in 0 Posts	Oil in Air-Con Gas I've just talked to a mechanic in a garage that does re-gassing. He reckons that when the gas is extracted, the machine measures the amount of oil that comes out and so they put the same amount back in when re-gassing. That's fine if the amount in there was correct to start with. I suspect that my air-con is low on oil, even though it was re-gassed by Kwik-Fit twelve months ago, as it whines a bit in use. It doesn't sound like the belt to me. So how do I know that the amount is correct? When they suck out the gas and oil using a vacuum it won't remove anything like all the oil apparently, but the longer they leave the vacuum on the more should come out. This guy looked up the total amount in a 75 on his computer and came up with the figure of 100ml which surprised him as he expected it to be a lot lower. I've now noticed that in a previous post TC added to the photo of the label above the grill under the bonnet 'Nippon Denso 8 oil, Amount: 110-130ml. This would presumeably amaze him. Is he a bit switched off or is this all a bit academic? I'm not well up on air-con and I don't want to risk a disaster. John Wright Last edited by jcwatrichmond; 13th July 2011 at 13:55..

13th July 2011, 20:37	#2
eddiemc05 Gets stuck in Mg zt ctdi Join Date: Jul 2010 Location: newcastle n.i Posts: 537 Thanks: 76 Thanked 23 Times in 22 Posts	Its called pag oil, a machine will take out as much as it can, the same amount wilk go back in as long as the operator has filled the bottle correctly and should introduce another 10 ml or so u can tell the machine how ever much extra u want, __________________ Mg zt 2004 cdti

13th July 2011, 21:36	#3
chrissyboy This is my second home lovely little ford focus. Join Date: Jul 2009 Location: East Dulwich Posts: 7,877 Thanks: 2 Thanked 82 Times in 68 Posts	our machine has all the cars specs stored so it takes out what is in there and puts back the amount that is supposed to be in the car ... __________________ [ I'm really confused. -I keep dreaming I'm an insomniac

13th July 2011, 22:01	#4
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,753 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	The oil is dissolved in the refrigerant when it's liquified. When the refrigerant turns to gas in the low pressure circuit, the oil in that portion stays put on the surfaces of the pipes/compressor inlet etc. Oil will also be carried through in very fine droplets of refrigerant vapour. That's basically how it lubes the compressor. When they empty the aircon system, they'll get as much of the refrigerant out in liquid form they can. The oil comes with it. When all the liquid's out, they'll evacuate the system to get any residual refrigerant and moisture out. Whatever oil is in there at this stage stays in the system because it's not volatile. So, some small amount of oil will remain after they've vacuumed it down for a while. I'd say the weight left will be trivial and is probably ignored. So, when they recharge with refrigerant, they should add the mean volume of the Nippon Denso 8 that's stated on the photo. You should ensure they add this amount, which may not be what 'the computer' says they should add. I guess the specified Nippon oil is the same stuff as is universally added, though I have seen no confirmation of that. This is the label. TC Last edited by T-Cut; 13th July 2011 at 22:03..

14th July 2011, 07:45	#6
SD1too Doesn't do things by halves Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007 Location: Former Middlesex Posts: 20,380 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	John, To be fair to the garage mechanic I think he was just covering himself against being held responsible for any complaints. But I agree that he should be able to determine the correct amount of refrigerant oil. I suspect that many operators have bought an air con. machine to increase their turnover but don't have a great deal of experience in the field. My real concern would be about Kwik-Fit. Did they add the correct amount, or indeed any oil when they recharged your system? I know that they're cheap, but they're not air con. specialists. Exhausts and tyres are their mainstay. They just added air con. to their list of services to expand the business. After previous dissatisfaction I've found an excellent self-employed mobile air conditioning chap. He comes to my house so I can see for myself what he's doing. He's not cheap, but is very thorough. It's an option you might like to consider. Simon. __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.

14th July 2011, 07:19	#5
jcwatrichmond Loves to post Rover 75 1.8T 2003 Club SE Join Date: Jan 2009 Location: Solihull, Posts: 370 Thanks: 0 Thanked 0 Times in 0 Posts	Thanks for the information. It seems that the garage mechanic that I first mentioned doesn't know too much about it and should be avoided in future. He was only going to add the same amount as had come out plus 5ml, so how much was in there was anyone's guess. JCW

15th July 2011, 07:49	#8
jcwatrichmond Loves to post Rover 75 1.8T 2003 Club SE Join Date: Jan 2009 Location: Solihull, Posts: 370 Thanks: 0 Thanked 0 Times in 0 Posts	This air-con refilling seems to be a bit of a 'black art'!! JCW

15th July 2011, 14:22	#10
James.uk Passed Away 2002 Pale Blue. Rover 75 CDTi Connoisseur auto. 170K miles Join Date: Dec 2008 Location: Near the M67. Posts: 14,509 Thanks: 199 Thanked 585 Times in 397 Posts	From what I have seen, and remember my mech doing --- He messes with the lil panel on top and I think - he tells it what make model the car is..? he then turns it on and leaves it. The machine removes what's in there, then replaces it with the correct amount for the car.. I then get billed for the amount used in the refill, less the amount that was already in there... innit??? It does put both dye and some lubricant into the system.. ...