DIY vehicle re-gas with CRC AC Charge

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David321

342 posts

Ultimate Geek

#302201 7-Nov-2022 10:22

Hi all,

After putting up with less than satisfactory AC in my wifes Nissan Dualis, I thought id buy a can of the AC gas from supercheap auto and put some in before spending at minimum a few hundred (I know from estimates) at the AC places.

Before gassing the air was cold, but not cold enough, hence why I thought more gas was needed, I connected the gage that comes with the can to find the pressure was reading about right where you would want it (between the green and yellow), I decided to put some gas in anyway to take it right up to the yellow, I emptied a little and checked the gage and found it was reading the same as when I started, so i did more and checked again, still the same. I eventually emptied the whole can, and still no change on the gage.

The AC still worked but not noticeably better, the next day the AC did not work well as the compressor would start and stop, classic symptom of over pressured system, then a few days later its working awesome and has done ever since.

I suspect there may be a leak in the system, if you consider it did not work well, then after gassing it was showing signs of to much gas, and now its working really good (the excess gas leaked out?).

I told my local AC guy who shook his head after I told him I gassed it myself with CRC (pretty much all AC guys do that as the stuff probably costs them a lot in business), he said the gages on the cans are crap (I believe him), so I am looking on aliexpress for a set of gages so I can see if my system is leaking, and when I top it up again I can use the proper gages rather than the CRC ones.

Has anyone had any experience with anything similar? or can perhaps offer some advice? Id be interested to hear about it.

_David_

richms

26404 posts

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#2992886 7-Nov-2022 10:55

Friend got a car that had clearly been just topped up right before they bought it. Re did it and it was right again for a few weeks before starting to slowly crap out again. I guess they are the radiator stop leak and head gasket repair liquids of the aircon world.

Richard rich.ms

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johno1234

1341 posts

Uber Geek

#2992894 7-Nov-2022 11:10

On the subject - anyone got a recommendation for a car aircon service in central Auckland or East Tamaki? Wife's 2006 Landcruiser Prado aircon is pumping ambient temperature air... not ideal with summer around the corner!

CoolCar are in East Tamaki - are they any good?

tripper1000

1539 posts

Uber Geek

#2992916 7-Nov-2022 11:43

Yeah, my car also had anaemic A/C and I watched a bunch of youtube video's of professionals explaining the processes before buying the CRC. I bought a set of gauges (off trademe) before using the CRC (as much for a learning experiment than trying to avoid the cost of a professional). When I overcharged the system (semi-intentionally) I was able to make an adaptor to use the gauge set to return some gas to the CRC can and get the system back in order.

You really need a set of gauges to see what is going on because reading the low pressure side (i.e. the gauge on the can) on it's own doesn't tell you the whole story - that can be correct and the system still won't work right. A professional can diagnose faults in the system based off of the the high and low gauge readings (such as a dirty evaporator, faulty TX valve or stuffed compressor).

You also need to find and download the cars service manual because you need to recalculate the pressures based on ambient temperature and engine RPM. There are setup parameters such as running the A/C fan full speed with the doors open (or not depending on the OEM).

There is also other indications that the system is over/under-charged that professionals watch for - such as the low pressure return line frosting up and bubbles (or lack-there-of) in the sight-glass. Liquid making all the way back to the compressor can be really bad/costly.

Those cans are bad-idea if the system is completely depleted for any reason. Technically you have to suck all the air out before putting the gas is. Oxygen reacts with refrigerant (or something), and air does not compress like the refrigerant so it negatively affects performance etc. Also there is supposed to be a particular amount of lubricating oil in the system, and that is likely to out of wack when replenishing with a CRC can. I believe professionals will blow out the remaining oil and measure-in new oil to be certain the system has the right load.

Long story short, it is way more technical that the instructions on the can make out, and a can-job is really only suitable for a few specific circumstances.

Don't take my word for gospel, I'm happy to defer to any professionals who chime in.

SATTV

1480 posts

Uber Geek

#2992918 7-Nov-2022 11:44

I have used these guys and they were very good.

https://www.coolcar.co.nz/centres/henderson/

I have also used Artic Autos and would not recommend them.

John

I know enough to be dangerous

tripper1000

1539 posts

Uber Geek

#2992926 7-Nov-2022 11:54

By the way, the pressure in the system goes up and down depending on temperature due to the gas expanding/contracting. Long-term the gauges will tell you if it is leaking but not really in the short term.

In the work-shops they suck all the air out of the system (so there is nothing left in there to expand and contract with temperature) and look to see if air gets air back in there. They can reliably prove it is leak free (or not) in minutes. For a potential slow leak situation they can put a dye in that reveals where slow leaks are after a few weeks/months.

David321

342 posts

Ultimate Geek

#2994352 10-Nov-2022 13:01

tripper1000:

Yeah, my car also had anaemic A/C and I watched a bunch of youtube video's of professionals explaining the processes before buying the CRC. I bought a set of gauges (off trademe) before using the CRC (as much for a learning experiment than trying to avoid the cost of a professional). When I overcharged the system (semi-intentionally) I was able to make an adaptor to use the gauge set to return some gas to the CRC can and get the system back in order.

You really need a set of gauges to see what is going on because reading the low pressure side (i.e. the gauge on the can) on it's own doesn't tell you the whole story - that can be correct and the system still won't work right. A professional can diagnose faults in the system based off of the the high and low gauge readings (such as a dirty evaporator, faulty TX valve or stuffed compressor).

You also need to find and download the cars service manual because you need to recalculate the pressures based on ambient temperature and engine RPM. There are setup parameters such as running the A/C fan full speed with the doors open (or not depending on the OEM).

There is also other indications that the system is over/under-charged that professionals watch for - such as the low pressure return line frosting up and bubbles (or lack-there-of) in the sight-glass. Liquid making all the way back to the compressor can be really bad/costly.

Those cans are bad-idea if the system is completely depleted for any reason. Technically you have to suck all the air out before putting the gas is. Oxygen reacts with refrigerant (or something), and air does not compress like the refrigerant so it negatively affects performance etc. Also there is supposed to be a particular amount of lubricating oil in the system, and that is likely to out of wack when replenishing with a CRC can. I believe professionals will blow out the remaining oil and measure-in new oil to be certain the system has the right load.

Long story short, it is way more technical that the instructions on the can make out, and a can-job is really only suitable for a few specific circumstances.

Don't take my word for gospel, I'm happy to defer to any professionals who chime in.

Interesting, I actually thought you were a pro until your last sentence which implied you are not? seems you know a fair bit about them anyway.

I suspected I overcharged my system, my compressor will occasionally switch on and off relatively quickly, which obviously means there is hardly any cold air as the compressor needs to stay on longer than it does.

An AC guy told me that is a classic sign of an over chraged system, as the compressor switches off when pressure is to high, then when the compressor is off the pressure drops so the compressor starts again, builds the pressure to high then switches off again, causing a never ending circle of on and off.

I drained some gas last night from the low pressure port using a screwdriver and seen some dye come out also, making me wonder if someone had tried to find a previous leak. Draining some gas has caused the compressor to work continuously again, but for how long I am yet to find out.

I am interested in the gauges you bought, they hook up to the high pressure port also? what reading should you get on both gauges? I understand most cars should be about 45psi max on the low pressure line with the compressor running. Also, how much were the gauges?

_David_

Andib

1297 posts

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#2994403 10-Nov-2022 15:40

David321:

I drained some gas last night from the low pressure port using a screwdriver and seen some dye come out also, making me wonder if someone had tried to find a previous leak. Draining some gas has caused the compressor to work continuously again, but for how long I am yet to find out.

FYI releasing refrigerant into the atmosphere is illegal under climate change response act 2002

https://www.epa.govt.nz/assets/Uploads/Documents/Hazardous-Substances/Guidance/899697bf28/Releasing-refrigerants-is-illegal.pdf

Signing up for Frank Energy? Use my referral and we both get $50 credit.

tripper1000

1539 posts

Uber Geek

#2994747 11-Nov-2022 15:29

No I'm not a profession, just have played around with it a little bit.

https://www.trademe.co.nz/a/motors/car-parts-accessories/search?search_string=airconditioning%20gauges

There are sets of gauge starting at $68 on trademe.

Yes gauges plug into both high and low sides. They have a 3rd pipe which is the connection for adding/removing gas, but isn't compatible with the CRC cans. The gauges usually have multiple scales and sometimes have colour bands to show the optimum pressures for the different types of gas. Some also some have scales for corrections needed due to ambient temperatures.

For interpreting the readings, google is your friend. Here is one of the first hits that seems to cover the basics:

https://carcody.com/r134a-low-side-pressure-chart/

Normal pressure for R134 at 21 deg C, low side should be 35-40 PSI an high side 145-160 PSI. High side will be too high if the system is overcharged (or if the condenser can't get rid of all the cold because the fan isn't working of the condenser is dirty/clogged or the air filter is blocked or your air vents are closed etc). If it is leaking the low side will stay the same until the very end, but the high side will get lower and lower over time (assuming everything else is constant - eg temperature, RPM & airflow).

The right way to fill the system is to vacuum out the remaining gas and weigh back in the OEM specified weight of gas as per the manual. For a DIY there are other, less correct ways to get it about right. Using gauges, you can fill it until you get the right high and low pressure readings - this is probably the best way (or least worse way) because you won't blow it up by over filling it.

Or you can look at the sight glass. This lets you "see" what is going on. It is a clear glass disk that is a window into the pipelines and is typically on the drier, somewhere close to the radiator. It is a good initial place to look before breaking out the can of CRC. Generally, if you think the system needs topping up but the sight glass shows mostly liquid, something else is wrong. If it shows lots of gas and not much liquid, it could be low on charge, or the compressor or TX valve is a bit sad. As you fill an empty system you will see more and more liquid flowing through the sight glass and less and less gas. Spurts of liquid and gas generally mean the system has got some but not enough gas. Just as you go from spurts to a near continuous flow of liquid with some bubbles in it, you are in the "just right" zone on most systems. If it is continuous liquid with no bubbles, you are somewhere between just right and too much. But these are general rules with exceptions. Variation in design mean it can be normal for some systems to have more bubbles/spurts and other systems to have no bubbles continuous liquid.

tripper1000

1539 posts

Uber Geek

#2994750 11-Nov-2022 15:37

P.S. there are invisible dyes that they put in the system that don't show until you shine a UV light on it. I assume this is so that the dye don't stain carpets etc. Leaks can also be evident through dust sticking to the leaked lube oil - but not always.

johno1234

1341 posts

Uber Geek

#2994902 11-Nov-2022 20:45

To the Prado into Coolcar East Tamaki. They confirmed that the refrigerant has leaked out through the condenser. Replacement condenser, re-gas and labour estimated at around $1300 ouch!

Scott3

3340 posts

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Lifetime subscriber

#2994945 11-Nov-2022 23:42

Wow $110 for CRC AC Charge Refrigerant R134a Refill & Hose - 400g

Old way to do this was to get a hose with a gauge for use with cheap R-134a air duster can's.

Never did a DIY regas myself, but have had the pro's do it twice.

First time was on an about 12 year old corolla. Cheap deal came up on a daily deal site, and I figured I might was well get it done, for the on going health of the system and to and see if the air -con worked better afterward. Didn't notice a difference on the latter point.

Second time was on a hybrid of similar age. A hybrid specialist mechanic when I did a per-purchase battery check was asked what other issues the car could have, and advised that the aircon compressor electric motor is within the refrigerant, and a special non-conductive lubricant is used, that can go conductive over time. Recommended the oil be changed and the system degassed about half way through the vehicles life, so I had it done.

Note that when the system is professionally regassed, a vacuum pump is used to evacuate the system of all refrigerants and contaminates. Then the system is refilled with fresh refrigerant. So quite different from topping off with a diy can.

In OP's position, I would probably call time on doing it DIY, and have a full regas done, rather than sinking more money into gauges etc.

empacher48

347 posts

Ultimate Geek

#2994950 12-Nov-2022 01:54

johno1234: To the Prado into Coolcar East Tamaki. They confirmed that the refrigerant has leaked out through the condenser. Replacement condenser, re-gas and labour estimated at around $1300 ouch!

I’d take that price any day over my $2,500 bill to replace the condenser in a Peugeot 407, and then re-gas.

It was about $600 for parts and gas, the rest on labour.

johno1234

1341 posts

Uber Geek

#2994953 12-Nov-2022 06:15

Yep about the same parts price for me.

robjg63

3837 posts

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#2995005 12-Nov-2022 08:40

johno1234: To the Prado into Coolcar East Tamaki. They confirmed that the refrigerant has leaked out through the condenser. Replacement condenser, re-gas and labour estimated at around $1300 ouch!

Interesting... I have a 2016 Mitsubishi Outlander that had the aircon expire earlier this year.

Took it to the dealer and they eventually found the condenser had a leak after doing some pressure tests etc. So needed a new condenser, re-gas etc and cost the same amount as yours ($1300). They apologised for the amount. I had been reading on possible costs if the compressor had expired and was actually relieved it was 'only' $1300!

Nothing is impossible for the man who doesn't have to do it himself - A. H. Weiler