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Old 1st May 2015, 20:33   #1
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Default Air-con Refrigerant: How much to fill?

Mods,
Please merge with the relevant thread if need be. I have created this thread so that we can discuss whether the AC Gas needs to be refilled to its fullest capacity-varies according to the vehicle- From Small Car-Large Hatchback-Sedan-MUV-SUV-Luxury Car.

Most of us have seen that the AC Mechanics just fill the AC Gas with a 500gms Can. But as we know that the AC Gas Capacity varies according to the Compressor Capacity and also the vehicle.

If 500gms of Gas is filled in a Small Car or a Compact Sedan, it would be sufficient. But what about a MUV or a Luxury Car. It could not be enough to cool the entire cabin due to lack of Correct Level of Gas in the AC Systems of those Large Cars.

So my question is whether to fill the AC Gas to its fullest capacity (How to find out the capacity if the Sticker-under-bonnet showing the capacity is torn out) or just fill 500gms of Gas and use the vehicle?
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Old 1st May 2015, 21:24   #2
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Default re: Air-con Refrigerant: How much to fill?

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Originally Posted by IndigoXLGrandDi View Post
So my question is whether to fill the AC Gas to its fullest capacity (How to find out the capacity if the Sticker-under-bonnet showing the capacity is torn out) or just fill 500gms of Gas and use the vehicle?
From what i know, gas quantity differs in each car based on the system. Traditional method of filling is using pressure gauges where gas is filled till suction gauge reads around 30 and high pressure gauge reads around 250. These values do change with temperature. But to me the best method is to use a Bosch automatic machine. The machine comes with a user manual which has a chart showing the gas quantity for most of the vehicles sold in India. Hope this is helpful.
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Old 1st May 2015, 23:11   #3
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Default re: Air-con Refrigerant: How much to fill?

Irrespective of whether the sticker has been torn off, each car model will have the quantity of refrigerant (in grams) and of lubricating oil (in ml/cc) specified in the garage manual (in the HVAC section). There is no one quantity fills all formula here. The measuring can either be done with an automatic AC gas recovery & filling machine, or by weighing the cylinder of refrigerant on an accurate digital scale.

For example, in the Scorpio (the Refresh model), the requirements are:
Refrigerant R134a - 830 +/- 20 grams
Compressor oil FD46XG - 150 ml

whereas in my Swift (2006) the requirements are:
Refrigerant R134a - 370 +/- 20 grams
Compressor oil 99000-99095-00A - 50 +/- 10 ml

In case you cannot find out on your own, write in to / call your AC system manufacturer (usually Subros, Behr or Denso in India), and they'll happily share the technical data with you. Or ask on Team-BHP!

Hope that answers your question.

Last edited by SS-Traveller : 1st May 2015 at 23:13.
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Old 2nd May 2015, 09:51   #4
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Default re: Air-con Refrigerant: How much to fill?

Our Xylo's AC is not cooling enough in the hot afternoons. Also the AC keeps making Hissing Sound every now and then. I can understand that the AC Gas needs refilling. But how much?
Last time my AC FNG refilled 500gms Gas from a sealed 500gms container but no compressor oil saying that the Container has oil also in it.
But I doubt Xylo needs much more than that due to Double AC Blower (Front and Rear). So how can I get the required quantity of AC Gas filled in our Xylo? Can I ask the FNG to refill Gas from Two 500gms Container? What happens if I fill 1000gms of Gas in place of say 850gms (Lets assume Xylo has identical capacity to that of Scorpio)?Also should the Compressor oil filled before refilling Gas or after?
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Old 2nd May 2015, 09:57   #5
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Default re: Air-con Refrigerant: How much to fill?

If I remember correctly my Civic after full evacuation took in about 530g. To the amount may be about right. Most small mechanics go by the pressures on the intake and exhaust.
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Old 2nd May 2015, 10:12   #6
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Default re: Air-con Refrigerant: How much to fill?

Quote:
Originally Posted by IndigoXLGrandDi View Post
...AC Gas needs refilling. But how much?
Last time my AC FNG refilled 500gms Gas from a sealed 500gms container but no compressor oil saying that the Container has oil also in it.
No, the oil has to be added separately.
Quote:
Originally Posted by IndigoXLGrandDi View Post
So how can I get the required quantity of AC Gas filled in our Xylo? Can I ask the FNG to refill Gas from Two 500gms Container? What happens if I fill 1000gms of Gas in place of say 850gms
Not recommended. An overloaded system with surplus gas will not only not produce cooling, but damage the compressor.
Quote:
Originally Posted by IndigoXLGrandDi View Post
(Lets assume Xylo has identical capacity to that of Scorpio)?
The Xylo has a Subros system while the Scorpio's AC is supplied by Behr.
Quote:
Originally Posted by IndigoXLGrandDi View Post
Also should the Compressor oil filled before refilling Gas or after?
Before.
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Old 2nd May 2015, 16:00   #7
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Default Re: Air-con Refrigerant: How much to fill?

So should I get only 500gms Gas filled after filling Compressor Oil for our Xylo? Will it be sufficient?
Can I buy the Compressor oil from local shop and what quantity and brand (or specification)?
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Old 2nd May 2015, 16:35   #8
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Default Re: Air-con Refrigerant: How much to fill?

Quote:
Originally Posted by IndigoXLGrandDi View Post
So should I get only 500gms Gas filled after filling Compressor Oil for our Xylo? Will it be sufficient?
Can I buy the Compressor oil from local shop and what quantity and brand (or specification)?
R134a required in Xylo = 580 +/- 20 grams (as said by technician, without referring to manual - can vary by 20-30 grams).
Compressor oil required = 150 +/- 20 ml.

So a 500 gram can is insufficient, and 2 such cans are far too much.

Where is your nearest Subros authorized service centre?

From Solapur (your location), the nearest Subros own service centre is at Chakan (Pune).
The contact person is
Mr. Sunil Rohila 98811 91712 Email : sunilrohila@subros.com
Subros Limited
B-8&9, MIDC - Chakan Industrail Area,
Chakan - Telegaon Road, Chakan,
Pune (Dist) - 410 501
Tel:(02135)-663131, 663140

Perhaps you'd like to call /email him for technical information.

Last edited by SS-Traveller : 2nd May 2015 at 16:44.
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Old 2nd May 2015, 17:11   #9
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Default Re: Air-con Refrigerant: How much to fill?

Thanks SS Traveller.
I called Mr. Sunil Rohila and he told me that the quantity of Gas is 600gms and that of Oil required is 20ml (40 ml in my case since I did not fill oil during last refills).

He explained me the procedure for refilling as well.
It was nice to talk with him.

Thanks once again SS Traveller.
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Old 2nd May 2015, 17:19   #10
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Default Re: Air-con Refrigerant: How much to fill?

Quote:
Originally Posted by IndigoXLGrandDi View Post
...Oil required is 20ml (40 ml in my case since I did not fill oil during last refills).
I think he is talking about a top-up of oil before gas charging, and not the full quantity of oil required.
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Old 2nd May 2015, 17:34   #11
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Default Re: Air-con Refrigerant: How much to fill?

I asked him whether 500 gms will be sufficient to which he advised me to get the Pressure checked at Low Pressure (LP) end and High Pressure (HP) end. LP should be @2 bar and HP should be @15-16bar. If they are, then no problem even if 100gms is less.

He advised me to get the Leak Test done, then Vacuum, Fill Oil, (again vacuum if the oil is not filled through Air tight Pipe to avoid air entering the system), then fill gas.
When I asked him oil quantity, he told 20ml. I asked will 20 ml be enough. He asked whether I changed Compressor or any part thereof before to which I replied negatively.
Also I told him that I did not fill oil during last 2-3 refills, he advised me 40ml.

Last edited by IndigoXLGrandDi : 2nd May 2015 at 17:35.
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Old 3rd May 2015, 01:44   #12
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Default Re: Air-con Refrigerant: How much to fill?

This thread could not have come at a better time.
Summers are here in full swing and many people would be facing AC issues.

Today drove our Honda City (CityZX) 2006 for about 20 KM at around 11AM and came back at around 1PM. The air out of the vents was moderately cool at best. the rear seat could not even tell if the AC was on and had to open the window!!
The AC never made it feel like a deep freezer even on day of purchase, which i guess is due to the huge glass area, but it has been getting weaker ever since. Got the AC gas refilled about 3 years ago i think but the cooling did not improve much. maybe due to incorrect amount of gas.

Can someone tell what make the Honda City AC is ?? and how much Gas & Oil is required?

Is this mentioned somewhere? how can one find out what make compressor is in a car?

Last edited by GTO : 4th May 2015 at 13:32. Reason: Do NOT use acronyms (e.g. NHC) when referring to cars. Full make & model please
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Old 3rd May 2015, 13:38   #13
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Default Re: Air-con Refrigerant: How much to fill?

Looked into the engine bay and found a sticker that says 'HFC-134a refrigerant R134a'.
a motor kind of thing below the engine that has a blue sticker which says
"HONDA DV4DF -12v - 47 - Denso India Ltd"
is this the AC Unit?
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Old 3rd May 2015, 22:32   #14
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Default Re: Air-con Refrigerant: How much to fill?

Quote:
Originally Posted by guptavis View Post
"HONDA DV4DF -12v - 47 - Denso India Ltd"
is this the AC Unit?
No, that is the starter motor.
Quote:
Can someone tell what make the Honda City AC is ?? and how much Gas & Oil is required?
Honda ACs are made by Denso India.
Gas (R134a) - 400 +/- 25 grams.
Compressor oil - 85 +/- 10 ml.

Last edited by GTO : 4th May 2015 at 13:32. Reason: Quoted post edited
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Old 13th May 2015, 02:49   #15
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Default Re: Air-con Refrigerant: How much to fill?

As the summer came and here we come the Indian Car owners with need to fine tune our car A.C. Cooling.

one thing I would like to clarify, here before I write anything further,
You don't need to Add compressor oil if your car Air-con is working, it would need to be added only when your gas has leaked completely, or the entire system has been service and flushed.

If the cooling is not as per mark, and you feel it cools only in early morning and late evening (after sunset) then all you need is Freon top-up, that too would not be needed in full required capacity of the compressor as the A.C. is in working condition and already has Freon in the system.

In case of less cooling, all you need to do is, attach a manifold guage and measure the pressures, in most cases it would only need to monitor low side pressure and add little bit of Freon to the system, most small cars would need anything between 150 grams to 300 grams max of Freon on a working car A.C.
If A.C. clutch is not engaging then you have more complex and expensive things to deal with.

Cutting long post short, I myself filled Freon on 5 vehicles in last 7-10 days,
I bought manifold gauge just for myself but seems all my friend circle is after me to get the top-up. (as its cheaper and they have some confidence on my D.I.Y stuff)
I also did a thorough video while fine tuning A.C. on my Santro and the video should be available on YouTube in a next 2-3 days max.

Just to remind you again, don't fill OIL until its flushed, or pump more gas to get more cooling, you would end up with shortened compressor life this way for sure.
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