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    Default Air Conditioning regas

    Following adverse comment on the belt snapping thread, here is a new thread to discuss air conditioning regassing.

    What are reasonable vent temperature targets with R134 refrigerant on a warm day car stationary?
    What are accepted maximum high side pressures in the above conditions?

    I recall achieving vent temperatures of 3-4degrees when using R12. Is this possible with R134?

    Mention was made about "sweating" lines being undesirable. Surely this is normal on suction lines near the compressor.

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    Thanks for your input.

    Farmpug

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    Sweating lines on all but low temperature cool room systems are pretty well a myth in my opinion. And on cool room systems it the "frost line" that seems to be bandied around. Many suggest charging until a certain frost line length is evident.

    Un-insulated metallic lines lower than the ambient temperature, especially in humid conditions, will always have condensate dripping from them. This is due to the laws of thermodynamics rather than a fault in the aircon system.

    In commercial and domestic systems refrigeration lines have insulation to prevent dripping and damage to the surroundings.

    The basic "feel" test is get close to the compressor and grab the suction (lo side) line. If it is bittingly cold that a pretty good indication that all is working well. If the fitting is condensing liquid , so be it.

    Neoprene hoses, pretty well to stop most other feel tests on the lo side. Unless you can access the liquid line where it connects to the evaporator, which should be similarly cold.

    Any experienced auto air tech will be able to diagnose your system.

    As I said in the other thread and DC has mentioned too. Pressures vary wildly depending on heat load on the evaporator and airflow through the condenser.

    So discussing absolutes may not be helpful.
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    Thanks Robmac,

    I understand your reluctance to answer about the pressures.
    but,
    What are reasonable vent target temps?

    Thanks

    FarmPug

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    Quote Originally Posted by Farmpug View Post
    Thanks Robmac,

    I understand your reluctance to answer about the pressures.
    but,
    What are reasonable vent target temps?

    Thanks

    FarmPug
    he's going to have to just pull a figure out of mid air. it will depend on the heat load on the system... how hot it is outside etc....
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    4-7 c air temp at vents on low speed, after an extended series of compressor cycles, with a ram air fan on the condenser. At 28 C + ambient.

    And a bit higher on high speed.

    However, it can vary widely depending on the vehicle ducting and distance from evaporator
    Last edited by robmac; 22nd February 2018 at 05:43 PM.
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    Quote Originally Posted by robmac View Post
    4-7 c air temp at vents on low speed, after an extended series of compressor cycles, with a ram air fan on the condenser. At 28 C + ambient.

    And a bit higher on high speed.

    However, it can vary widely depending on the vehicle ducting and distance from evaporator
    And how long the AC has been switched on to cool the cold air flow pipe system, I reckon. A baking hot dashboard and stuff can take a wee while to reach "maximum cold".
    JohnW

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    Quote Originally Posted by JohnW View Post
    And how long the AC has been switched on to cool the cold air flow pipe system, I reckon. A baking hot dashboard and stuff can take a wee while to reach "maximum cold".
    I thought the following phrase would have covered that.

    after an extended series of compressor cycles,
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    Quote Originally Posted by robmac View Post
    I thought the following phrase would have covered that.

    Fair enough, you are completely correct! Thanks.
    JohnW

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    Quote Originally Posted by DoubleChevron View Post
    he's going to have to just pull a figure out of mid air. it will depend on the heat load on the system... how hot it is outside etc....
    ...That is why I qualified the question.
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    Real cars have hydraulics DoubleChevron's Avatar
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    Quote Originally Posted by JohnW View Post
    Fair enough, you are completely correct! Thanks.
    The first CX with air conditioning I tried..... When it was 30 degrees outside, the air temperature from the vents was close to 50degrees............ However if you turned the A/C on it dropped to just below 40degrees. So the A/C was actually working

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    Quote Originally Posted by DoubleChevron View Post
    The first CX with air conditioning I tried..... When it was 30 degrees outside, the air temperature from the vents was close to 50degrees............ However if you turned the A/C on it dropped to just below 40degrees. So the A/C was actually working seeya, Shane L
    Very funny!!
    JohnW

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    R134a in a correctly designed system, operating under ideal (laboratory ?) conditions will reduce ambient temperature air by around 28 degrees C.

    You now may understand why Hycill name their R12/ R134a drop in replacement Hychill Minus 30.
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    Quote Originally Posted by robmac View Post
    R134a in a correctly designed system, operating under ideal (laboratory ?) conditions will reduce ambient temperature air by around 28 degrees C. You now may understand why Hycill name their R12/ R134a drop in replacement Hychill Minus 30.
    I didn't know that, so many thanks for the information.
    JohnW

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    Quote Originally Posted by robmac View Post
    R134a in a correctly designed system, operating under ideal (laboratory ?) conditions will reduce ambient temperature air by around 28 degrees C.

    You now may understand why Hycill name their R12/ R134a drop in replacement Hychill Minus 30.
    Interesting.
    Have you used Hychill? Any comments?

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    Quote Originally Posted by Farmpug View Post
    Interesting.
    Have you used Hychill? Any comments?
    I've used hychill - there is no doubt that it works well. And is superior to R134a as a refrigerant.

    However it's also extremely flammable (a "brother" of LPG), after having a "flame out" incident during a charging hose disconnection in the vicinity of the distributor I'm no longer so keen to use it.

    I got away with burnt hair on my arms. But with some ULP in the mix the result could have been catastrophic.

    So I'd always suggest that each vehicle owner and aircon service person decide for themselves if the improved system operation outweighs the risks.

    Many business's won't use Hychill or any other hydrocarbon refrigerants as a stated policy.

    This video details Hychill's engineering consultant demonstrating how safe the product is to use. Although I'm the first to admit his testing method may be flawed.

    https://www.youtube.com/watch?v=k0K1WPCWm2k

    It's worth watching in it's entirety or at least jump to to around 3:38

    After that, you will be in a position to decide if you want hychill in your car.

    Many on AF don't share my opinion, but that is the way of it.
    Last edited by robmac; 24th February 2018 at 04:12 PM.
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    I've used Hychill and straight LPG in several cars. You just have to be careful. Most fills are only a few hundred grams as compared to how many liters of petrol in your tank?
    But if you get your system fixed it should last/work for a long time with 134a. My 2000 Toyota's A/C hasn't been touched and it is still working perfectly well having done over 200,000km
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    Quote Originally Posted by JoBo View Post
    I've used Hychill and straight LPG in several cars. You just have to be careful. Most fills are only a few hundred grams as compared to how many liters of petrol in your tank?
    But if you get your system fixed it should last/work for a long time with 134a. My 2000 Toyota's A/C hasn't been touched and it is still working perfectly well having done over 200,000km

    However, how can you "be careful" when removing a Hi side charging hose ? You can't move charging port (located near the distributor)

    There no choice but to let some pressurized refrigerant discharge. Volume of refrigerant is not the issue, the blow torch like flame and potential to light up flammable materials is the real risk.

    Petrol in the tank isn't pressurized to to a few hundred psi as is refrigerant.

    I think what you may be saying "An accident hasn't happened to me". I can assure you it has happened to me and I've changed my mind about the safety of hydrocarbon refrigerants.

    Nippondenso aircon systems are among the best designed and most reliable auto aircon. They value proper engineering design.
    I'm not surprised you have had no issues in the Toyota.
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    Quote Originally Posted by JoBo View Post
    I've used Hychill and straight LPG in several cars. You just have to be careful. Most fills are only a few hundred grams as compared to how many liters of petrol in your tank?
    But if you get your system fixed it should last/work for a long time with 134a. My 2000 Toyota's A/C hasn't been touched and it is still working perfectly well having done over 200,000km
    I'm expecting a good run, and expect that I would have had but for a mechanical failure of a new condenser a few weeks after installation. the AC folk will replace it next week. And yes, it'll be 134a.

    Yes, a big tick for Nippondenso gear too.
    JohnW

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    Yes, a big tick for Nippondenso gear too.
    My very first "Egg" Tarago had ND dual air. It worked perfectly for 180, 000 km. Eventually it lost charge due an aftermarket cruise control (not fitted by me) rubbing on a hi side aluminium line and holing it.

    At the time I was busy running my own business, and stupidly trusted the local a/c "specialist" to do a repair.

    It worked for while, but within 6 months the compressor developed death rattles.

    At that stage I checked it out myself, and as I suspected the compressor had very little oil. The mob that did the repair obviously didn't replenish the oil lost from the leak.

    I fitted a new / used compressor topped up the oil and all well for another 50, 000 km, at which time I sold the vehicle.

    Denso systems stay working if serviced properly.
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    Quote Originally Posted by robmac View Post
    R134a in a correctly designed system, operating under ideal (laboratory ?) conditions will reduce ambient temperature air by around 28 degrees C.

    You now may understand why Hycill name their R12/ R134a drop in replacement Hychill Minus 30.
    My first reaction to this was "Hey, neat. I didn't know that" but, on thinking about it a bit more, it can only be under strict conditions as you say. The temperature at which the refrigerant evaporates is fixed by the chemistry and pressure in the refrigerant, not relative to the ambient temperature at all. You can cool very little air to this temperature or a lot more air to somewhere between ambient and the evaporation point -- depends on how much air you push past the evaporator.

    It makes sense for Hychill to categorise their refrigerants at easy to remember levels, but I suspect it's more to do with marketing than deep physics. i.e. you could concoct conditions for each of their refrigerants that would reduce ambient by about 30C -- then they could call them all the same thing!

    Not a flame or anything -- just thinking aloud.

    Have fun,

    Rob.

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    Quote Originally Posted by robs View Post
    My first reaction to this was "Hey, neat. I didn't know that" but, on thinking about it a bit more, it can only be under strict conditions as you say. The temperature at which the refrigerant evaporates is fixed by the chemistry and pressure in the refrigerant, not relative to the ambient temperature at all. You can cool very little air to this temperature or a lot more air to somewhere between ambient and the evaporation point -- depends on how much air you push past the evaporator.

    It makes sense for Hychill to categorise their refrigerants at easy to remember levels, but I suspect it's more to do with marketing than deep physics. i.e. you could concoct conditions for each of their refrigerants that would reduce ambient by about 30C -- then they could call them all the same thing!

    Not a flame or anything -- just thinking aloud.

    Have fun,

    Rob.
    Do some research about superheat, sub cooling, sensible and latent heat and you will become aware that cooling can continue after the refrigerant has boiled/ evaporated.

    In practice it can be difficult to get adjustments exactly right.

    Also, without fresh air intake, the recycled air repeatedly circulated has lower ambient temperature after each pass through the evaporator. Provided the cooling capacity is greater than the heat load.
    Last edited by robmac; 25th February 2018 at 11:12 AM.
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    Quote Originally Posted by robmac View Post
    Do some research about superheat, sub cooling, sensible and latent heat and you will become aware that cooling can continue after the refrigerant has boiled/ evaporated.
    "Subcooling" was a new new term to me, and it's nice to learn new terms, but neither was much of a new concept. So yes, to be sure, the refrigerant can continue to take heat from the air well above its evaporation temperature. I was saying much the same earlier when I said "somewhere between ambient and the evaporation point". Cooling the air below the refrigerant's evaporation temperature would present a challenge.

    Rather doubtful that my point, that "Hychill Minus 30" is more marketing/convenience than physics, merits a second posting, but here it is.

    Have fun,

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    Refrigerants are often categorized by a "short cut "description or purpose for which they are used.

    Possibly, Hychill have chosen to reflect this in their name. Hychill -30 is R12 / R 134a drop in replacement.

    Where as Hychill -40 is a substitute for R22, R502 or R404a, mainly medium temperature applications.

    If you look at their Sales page, it's obvious how they name their products.

    https://hychill.com.au/


    None of which alters the fact they are flammable and can be a hazard to technicians using them.
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    Real cars have hydraulics DoubleChevron's Avatar
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    my biggest concern with the hycill refrigerant .... it where it may be used in a closed space. It concerns me the thought of it being used in a small coolroom for example. I'm personaly not overly concerned about it use in cars. Most leaks are so incredibly small, you would never get to flammable levels.

    The biggest issue of course what if you crash and rupture the systems contents at once..... It would be a good fireball i reckon. Luckily if you burnt all 300grams at once.... it should be a at the front of the bonnet a long way away from you ... through a firewall.

    seeya,
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    '78 GS1220 pallas
    '92 Range Rover Classic ... 5spd manual.

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    Quote Originally Posted by DoubleChevron View Post
    my biggest concern with the hycill refrigerant .... it where it may be used in a closed space. It concerns me the thought of it being used in a small coolroom for example. I'm personaly not overly concerned about it use in cars. Most leaks are so incredibly small, you would never get to flammable levels.

    The biggest issue of course what if you crash and rupture the systems contents at once..... It would be a good fireball i reckon. Luckily if you burnt all 300grams at once.... it should be a at the front of the bonnet a long way away from you ... through a firewall.

    seeya,
    Shane L
    As you say, possibly OK in car. However I shudder to think what could happen if an evaporator developed a leak with the brushes of fan motor arcing away nearby. You don't need much propane to create an explosive mixture.

    However, not suitable for a bigger system like a 20 kw house system. With charge of upwards of 7 kg.

    Even my incident removing a hi side charging was "exciting" . And that was only a hose full at a pressure of 150 psi or so. The flame plume was pretty impressive.

    And there has already been one incident with a chiller plant using propane based refrigerant being destroyed.

    https://www.coolingpost.com/world-ne...ion-explosion/

    Although authorities are pretty coy about giving a detailed reason.
    Last edited by robmac; 25th February 2018 at 03:58 PM.
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