Air Conditioning Tech Thread.

[Rhyno]

Too right mate,

This is where the term "the AC must be out of gas and just need a top up" term comes from - to many dogey shops telling there customers made up bullshit - because it gets them repeat buisness each time it leaks out, or each time it gets hot.

Everything is changing now with so much awareness on global warming though, so this should happen less and less

[thechuckster]

Any suggestions for stores in Oz that could sell a seal and/or bearing kit for a 10PA17C compressor?

All I can find online is wholesale distributors for parts for Denso compressors - whereas in the US, there's workshps that seem quite happy to list and sell small parts direct to the public (e.g. like this guy) ... and I'm just waiting on a reply to a query to him about postage costs.

Suggestions for a good A/c workshop in Toowoomba Qld would also be greatly appreciated.

[dnegative]

Would be really good to hear the results dnegtive

Wont know for a little while, its going to piss down rain for a week here lol

[Rhyno]

Sorry bro only lived in Darwin. Had a look around though, and your right they do seem all oversea's. You could try calling local Actrol's or Heatcraft branch and see if they have anything on there books, thats where I go usualy in D-town for parts.

Hope that helps.

[dnegative]

Picked up the car today with some good and some bad news;

Good:
3deg at the vent, AC is icy cold
Less load on engine

Bad:
Compressor is noisy, he seemed to think it's either a shit reco or it's been starved of oil :S He got 240g of r134 out of the system which he said was well low (eh,It had a slight leak) and there was a suggestion it may not of had enough oil in the first place.
Heater tap may be weeping a bit

Aside from the bad news about the compressor I'm impressed with the results. If anyone in Sydney wants to give hychill a go the place is advance auto electrical in campbelltown, pretty honest down to earth bloke imo

[litldv8]

Suggestions for a good A/c workshop in Toowoomba Qld would also be greatly appreciated.

ashleys auto air in eyers street are good
talk to dave
neil

[Rhyno]

Thats good to hear dnegative, That sucks about the noise but at least its cold

The comp may get less noisy the more you run it, if it has been a while since it has been used as any gunk in the compressor (shards, old oil sludge etc) should get pumped out and held in the filter drier... or the comp may just stay the same.

All the best mate

[dnegative]

I'm hoping it just stays noisy

Will be waiting for a nice 35deg day now

[Z2TT]

Hychill HR12 (Now called Minus30) is a great refrigerant, I regassed my Soarer and Pulsar with it and it runs great. Soarer needs some things fixed but pulsar has a very good a/c system and can get -5 at the vents on a hot day, it get's so cold that it stings, ridiculously cold.

You do not need to change oil as Hychill is compatible with all oils found in A/C Systems.

I'm not a fan of pressure testing at very high pressures upward of 300 PSI it can create leaks in weak components as some cars condensers and evaporator are very poor quality, even though the A/C system is made to run under pressure some components such as the evaporator really don't see anything above 140 PSI.

Vacuum test can indicate if there is a leak sometimes but not indicate the location, if system is holding decent vacuum for decent amount of time you COULD assume that when the gas is put in it should last a fair bit, however in theory vacuum test may not show leaks on rubber hose ends as it might pull them shut, where as pressure would otherwise make them leak.

[Rhyno]

You don't need to change the oil in the comp, but since you have the system opened up - why not? It like changing an oil filter on a petrol engine without changing the oil...

I to am not a fan of pressure testing above 1000kpa in new cars, old cars older than 1990 I will take to 1500kpa if there is a very hard to find pin prick of a leak, as the evaps are generaly a bit more robust.

I work in kpa as it is more accurate, so to crunch the numbers;

1 Kpa (Kilopascal) = 0.145037738 Psi

145.037738 psi is 1000kpa. What discharge pressures do you usually see Z2TT with the ambient temps where you are? I'm assuming around the 150 psi mark???... And if there was a weak part that may leak, wouldn't it be good to do a true pressure test, close to what the customer will have his AC system operating at, so that if there is a leak it can be fixed straight away, not down the track after the customer has already invested time and money in his AC?

Yes you are correct about the Vacuum test - it may not show the leak, but help indicate its position e.g. bubbles disappearing from where you sprayed.

Z2TT - How do you know if your system is free of contaminants if you don't do a vacuum test?

[thechuckster]

thanks litldv8 & Rhyno. Will talk to those folks once I have the motor sorted.

[matty12]

If a condensor is of poor quality and it fails a pressure test @300 psi it's very possible that it will do it in service which is not what you want. 300 psi is not hard to get on some vehicles so it not out of reach for a system to get that high, yes its not suppose to but can get there. Alot of high fan speed thermos wont cut in until 250-280 psi, if its got a clutch fan even more of a chance.

Rhyno, do you mind sharing the formula for working out heat loads etc, im interested to know if i ever had to size a system for a older vehicle.

[Z2TT]

I don't know if it's just me, but many cars i've known of have had heaps of evaporator failures, giving me the impression that some evaporators are just very crap so to say, and if they are going to develop leaks where they have never seen pressures above 150 PSI pressure testing to 300 is pretty likely to make them leak and then bang $1500+ Dash out evaporator repair job where it might have lasted for a few years otherwise. I Guess it all depends how sensitive your gas sniffers are if you can detect leaks without pressure testing with too much pressure.

[Rhyno]

Yes there are some crap evaporater designs out there, and yes some of the newer ones will develop a leak at high pressures. A high quality leak tester such as the CPS LS3000 are a must to ensure you are acurately testing the system. CPS LS3000 The Eliminator

So after your 150 psi pressure test, Z2TT how do you know your system is free of contaminants?

Matty12, I just use a basic fomula, there are complex ones out there but this one is quite simple and easy to use, and taught to me by the grey nomads at my work. Its Just the dimensions of the vehicle (including the unocupied area's e.g. the boot/bonnet as they absorb heat from the sun) L x W x H, then multipied by 300 watts for vehicles with untinted windows, or 250 watts for the darkest legal tint. If the tint is somewhere in between pick a number between 250 and 300. Using this formula will get you very close to the outcome of complex heat load calculation. P.S. This works for sizing rooms in house's as well.

So the heatload for my Camry would be something like

3.3 m x 2.2 m x 1.4 m = 10.164 m3 (cubed)

10.164 m3 x 250 watts (dark tinted windows) = 2541 watts, or just over 2.5 kws

Hope that makes sense,

Kind regards,

Ryan

[matty12]

^^^ cheers for that.

I see what your saying Z2TT, old design evaps which are sepentine/tube and fin design can easily hold 300psi as they are thick walled tube used in those. I certainly would'nt test to 300psi on a VE commodore or anything new they are far thinner material to get maxium heat transfer through.


150psi is certainly not enough for any of the high side of the system considering that the pressures that they can run at, ive even see a high side gauge go up to as much as 450psi before the high side pressure switch drop the comp out, obviously there was a blockage in the system and was not normal operating conditions.