AC not delivering chilled air

[disco stu]

Swede: what are the real issues with the hydrocarbon refrigerants? Flammable doesn't seem a big issue to me considering the small amount used, especially compared to the large amount of high pressure fuel that can pour out given a similar issue that can affect ac lines. I've also heard that the bigger fire risk is atomized oil on an ac line puncture. From the large amount of reading I did, it seemed that the hydrocarbons were more efficient than R134a and therefore less stress on the system. Any idea what the denso compressors didn't like about them?

Reason for my interest in this is that I really don't like being held to having to visit professionals, based on cost and also workmanship. I've found with a lot things that I've payed for I get shoddy work done and end up having to fix it up, and I know that I do a better job myself (albeit slower, sometimes much slower!). I'm also the one that fixes issues that aren't fixed properly by professionals for friends ($1000 to not actually fix the issue with a falcon, that I worked out in 5 min of diagnosing and fixed in 30 min of work), so a fairly low opinion. I like the idea that with the hydrocarbons I can legally purchase and regas myself, although I've worked out a way of legally buying r134a, I just can't legally it put into my ac system, even though it's purpose for sale is for spraying into the atmosphere! Getting ac work done is just so expensive also

[Swede50]

Hmmmm!

Have heard this a lot over the years.
No question that "barby gas" works
Compressing a highly flammable gas and then condensing it to liquid in the condenser,,,,
There is a reason that it is illegal in NZ and in Queensland.
Victoria is all about self regulation,,,, with all those problems
If the system was designed for the gas it would be a reasonable refrigerant to some extent.
The new refrigerant taking over from R134a in automotive AC is R1234yf
That gas is also flammable but to a lesser extent.
Mercedes had a under bonnet fire in a controlled crash test and spent a lot of time arguing with the EU over it.
Re the Denso compressors
It is something to do with the case hardening of the cylinder walls.
As explained to me by a compressor engineer some years ago.
The cylinder wall and piston skirts are case hardened by the interaction of the oil and refrigerant.
Looks like the hydrocarbon upsets this somehow and the pistons wear rapidly
Could be the Denso oil???
Too many failures on Denso comps for it to be used in my opinion.
My largest complaint is that there are too many cowboys out there doing A/C work with little to no know how. There have been vehicles damaged by this refrigerant,,, explosions in the evaporator.
The latest I heard of was in WA.

[BruceandBobbi]

Some light reading.

http://www.dmp.wa.gov.au/Documents/Dangerous-Goods/DMIRS_IS_FlamRefrigGases.pdf

[disco stu]

Thanks. I'm amazed people got explosions to occur within the system-must be something really wrong there for ignition to occur within the AC system. Being sealed and filled with a hydrocarbon there should be no issue with flames occurring within (no oxygen). Same reason why I don't think its dangerous to compress and evaporate, which we do often enough. Once its out of the system though its a whole other story

The R1234yf sounds interesting-just did a bit of reading on it. While it seems very non flammable, the chemical changes it goes through on combustion are a different story (same with r134a if I'm correct). In a bad car fire I imagine this would happen, not that I'm worried about the car occupants here-they are already dead if they are near any of the bad gasses! Wonder if they will require certification to use?

What would the design differences be between the different gases, when you mention be alright if designed for it?

I asked about getting AC topped up, as it seemed to have no issue just slowly lost gas over many years (normal behaviour for vehicles I've been told)-$150 was the price. Just for that. Fair bit of a rort I thought as they were only adding gas to the system, not fault finding etc.

Appreciate your response, thanks

[erad]

$150 for the re-gas. I haven't had a re-gas for ages, but to me $150 sounds like a reasonable price. Yes - it is expensive, but I recall paying l= more than that 20 years ago, and $150 then bought a lot more than today.

[disco stu]

Well, my wife does say that I have unrealistic expectations on price sometimes!

[k100dennis]

So I did some research and got the name of a credible guy here. Called him and discussed the problem. He'll do a nitrogen pressure test, find the leak source, correct the problem then re-gas the system. Was very helpful on the phone and will be looking at it this Saturday morning. I'll post the outcome. Thanks all for your input.

[Swede50]

Hi,

$150 is OK for a service on the AC

The "topping up" of a AC system is long past.
They will recover any remaining refrigerant and the Vac out the system
Evacuation of the system for 20-30 min is very important as it boils off any remaining refrigerant and air in the system
As air is a non condensable gas it plays havoc in a AC system - high pressure
A fresh charge of refrigerant to the correct amount is important. Accurate scales
Usually a +/- 20Gm is specified
With a dual evap system as found in some of the Pajeros if the charge is not correct it will have too much when the front is running or too little when both are working
On a old vehicle I would recommend a new drier/desicant bag.
Also, UV dye is a good idea, it find the smallest of leaks not able to be found any other way. And every leak not just the big one they find first. Nitrogen pressure will only find a large leak.
The recommendation is to replace the drier every two years, basically it is like the oil filter for the AC system.

[spot01]

The compressor oil should also be changed.

[Swede50]

Thanks. I'm amazed people got explosions to occur within the system-must be something really wrong there for ignition to occur within the AC system. Being sealed and filled with a hydrocarbon there should be no issue with flames occurring within (no oxygen). Same reason why I don't think its dangerous to compress and evaporate, which we do often enough. Once its out of the system though its a whole other story

The problem is with the older cars that a lot of this is used in.
Evaporator leaks are not uncommon.
The evap leaks and the gas sits in the footwell ,,, door opens and a spark, though tiny, from the door switch seems to be enough..... or so I have been told.
There are a lot of opinions on both sides in this.

The R1234yf sounds interesting-just did a bit of reading on it. While it seems very non flammable, the chemical changes it goes through on combustion are a different story (same with r134a if I'm correct). In a bad car fire I imagine this would happen, not that I'm worried about the car occupants here-they are already dead if they are near any of the bad gasses! Wonder if they will require certification to use?

What would the design differences be between the different gases, when you mention be alright if designed for it?

The design differences would be in the hoses and pipe work for a start.
Also, the seals are not LPG rated. I would also think the condenser and evaporator would require different certification for LPG
Hydocarbon AC gas is a butane/propane mix, mostly


I asked about getting AC topped up, as it seemed to have no issue just slowly lost gas over many years (normal behaviour for vehicles I've been told)-$150 was the price. Just for that. Fair bit of a rort I thought as they were only adding gas to the system, not fault finding etc.

They are required by law to recover any refrigerant in the system and regas with a full new charge

Appreciate your response, thanks

Cheers

[juanchos]

Evaporator maybe?

I just replaced the front evaporator on mine BIG BIG job I did myself. The good news is that you do not have to remove the whole dash.

Now save yourself headaches!!!

I you need to replace the compressor you MUST replace the CONDENSER as well, this is a micro passage unit and easy plugs.

This is a sample video by Scotty Kilmer on condenser:

https://www.youtube.com/watch?v=U0O1mcnwjZs

NOTE: I also installed an cabin air filter not factory installed.

https://www.ebay.com/itm/2001-2006-Gen3-Mitsubishi-MONTERO-Cabin-Air-Filter-USA-Spec-LHD/392309579449?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

[k100dennis]

My issue was a blown fuse for the compressor power supply. It is fuse #19 in the large panel under the hood on the LH side. The auto elect couldn't find any other problems and did a full system check, gas pressure, flow and air temperature etc. All good now.