Home » Public Forums » GMCnet » Charging dash A/C with hydrocarbons - alternate method
| Charging dash A/C with hydrocarbons - alternate method [message #305055] |
Sun, 07 August 2016 10:16  |
gladius
Messages: 48
Registered: November 2015
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For those of you who'd like to get the best possible performance out of your dash air conditioner, without using poisonous/patented/underperforming DuPont crap (R12/R134a), as you may know Duracool is an excellent drop-in option that many here have had much success with. It contains a mixture of propane and isobutane. At $9 for a 6oz can however, it's not exactly cheap. Here is alternate way of charging an A/C with propane/isobutane that would be more suitable for an experimenter and/or cheap SOB like me, particularly if charging multiple vehicles, as it's much cheaper per can and more versatile.
-----
Items needed:
MSR IsoPro camp fuel 8oz -- $6/can, bought from the local Academy Sports and Outdoors. This contains 80% isobutane and 20% propane.
Coleman propane camp fuel, 16oz -- $3/can, can be found anywhere and everywhere. With the right fittings you can refill these from a larger bulk tank for less than 50 cents per pound.
Coleman propane extension host -- $27, from Amazon
Lindal valve to throwaway propane canister adapter -- $31, from Amazon.
Yellow A/C charging hose -- I bought a full set of three hoses for $13 from Amazon.
A gauge set is helpful, but not required.
------
You'll need to cut the yellow charging hose, cut the Coleman propane extension hose, and join the two together with brass fittings and hose clamps. The prices for everything have gone through the roof these days so expect to spend $15-20 for the fittings. I recommend installing a brass shut-off valve, especially if you don't have a gauge set. If your coach has been converted to R134a you should have quick disconnect fittings installed on the factory 1/4" SAE schrader valves. In this case you will need a female R134a quick disconnect adapter to connect your charging hose. I recommend getting the 90* fittings with a shutoff valve built in. Uxcell sells some nice ones on Amazon for about $13 each.
This guide assumes your A/C is already in basic working order; maybe low on charge, but with no major leaks or equipment failures. First start by evacuating the existing charge. I recommend venting the toxic DuPont crap into the atmosphere so it will never again have the opportunity to contaminate someone's A/C system. Otherwise if you feel it necessary for some reason, take it to an A/C shop and have them recover it.
You will need to decide what ratio of propane/isobutane you want to run, and calculate the charge amount accordingly. It's said that 60/40 propane/isobutane is the optimum ratio for drop-in R12/R134a replacement. This makes things simple, as if you charge the MSR IsoPro and Coleman propane in equal amounts, it will result in a 60/40 ratio. If the ratio is slightly off it doesn't matter. You can also experiment with different ratios depending on your desires, operating conditions, etc. People in extreme conditions and those wishing for better fuel economy/less compressor drag may want to run more isobutane; for better cooling per pound in normal climates use more propane. You can go as low as 20/80 propane/isobutane (using MSR IsoPro cans only; no Coleman fuel) or up to 75/25. The more propane you run, the higher system pressures will be, and the more load there will be on the compressor when it kicks in.
When the system is empty, you can begin charging. It's pretty simple. Just charge it the same way you would any other refrigerant, except using your new spliced together charging hose. Be sure to bleed all air out of the hose(s) before charging. The early coaches use 3.5 pounds (56 oz) of R12, and the late ones (77-78 I think) use 3.75 (60 oz.) For optimum charge with hydrocarbons, use only 36% of the R12 total. That's 20.2 oz on early coaches, 21.6 on late models. The amount charged does not have to be exact; you can go an ounce or two over without hurting anything. Remember, if a 60/40 ratio is desired, use equal amounts from the MSR IsoPro and Coleman propane. If other ratios are desired you will have to do some calculations to figure out the right amount to charge. Start your charging with the IsoPro first!! This way system pressures will start out low, and then will gradually increase as you charge in the propane. I recommend charging as a liquid by holding the can upside down, but be very careful to crack the valve open slowly and take your time with it so as not to accidentally slug the compressor by flooding it with liquid.
When you've finished charging, you will have COLD A/C! My coach on a 95-100+ degree day has no problem icing up the evaporator with the cycling switch shorted to run the compressor constantly. It will easily blow 35* temps out of the vents like this, but of course, this isn't sustainable as the evaporator will completely ice over. With the compressor cycling normally, vent temps will hit 43-44* with the evaporator alternately icing and thawing. That's the best you're going to get out of a stock GMC with its terribly restrictive heater/AC box and vent design, with no insulation. There is much more refrigeration capacity than is actually able to be used due to this poor design. It's good enough however; at idle and driving down the road the A/C works great and feels comfortable even with no privacy curtain installed to keep the cold air up front.
On a final note, some people make a big deal about the impurities present in camp fuel. It's true that camp fuel is not refined to the same degree as the base stock Duracool and other companies use. All propane sold in the USA is rated HD-5 which means it's at least 95% propane, with the majority of the rest being other hydrocarbon gases which are also themselves refrigerants and will not cause any problems. There may be a tiny bit of non-condensible gases in there, which isn't enough to harm anything, and won't be pulled into the system if you charge as a liquid. There is also likely to be a tiny bit of water vapor present, but again, this is harmless; your desiccant will absorb it quickly.
What I love most about doing things this way is that the refrigerant is CHEAP. It costs a bit of money to buy the necessary adapters and fittings, but I don't care as I love to acquire new tools that expand my capabilities. Having bought the necessary tools, the total refrigerant cost to fill up a GMC is $15, or about $10 not counting the refrigerant that's left over to be used on other vehicles. At these prices I can afford to stockpile a large quantity of refrigerant to fill all of my vehicles and others' too for decades to come. With the right fittings for my bulk tank I can also refill the propane cans for less than 50 cents each, which makes the propane cost practically nothing. This is especially useful for charging R22 systems, which can be done basically for free. Kiss my ass DuPont!
That pretty much covers it, but feel free to ask any questions you may have.
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| Re: [GMCnet] Charging dash A/C with hydrocarbons - alternate method [message #305056 is a reply to message #305055] |
Sun, 07 August 2016 11:25  |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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Your write up makes me think that it is so much simpler to just buy 3 cans of Duracool (HC12a) for about $21 and fill with that.
No need to buy hoses, cut and splice them, etc. The $86-91 you list for valves, hoses, fittings plus the associated labor will buy a lot of Duracool.
Emery Stora
77 Kingsley
Frederick, CO
> On Aug 7, 2016, at 9:16 AM, Nathan Cline wrote:
>
> For those of you who'd like to get the best possible performance out of your dash air conditioner, without using poisonous/patented/underperforming
> DuPont crap (R12/R134a), as you may know Duracool is an excellent drop-in option that many here have had much success with. It contains a mixture of
> propane and isobutane. At $9 for a 6oz can however, it's not exactly cheap. Here is alternate way of charging an A/C with propane/isobutane that would
> be more suitable for an experimenter and/or cheap SOB like me, particularly if charging multiple vehicles, as it's much cheaper per can and more
> versatile.
>
> -----
>
> Items needed:
>
> MSR IsoPro camp fuel 8oz -- $6/can, bought from the local Academy Sports and Outdoors. This contains 80% isobutane and 20% propane.
>
> Coleman propane camp fuel, 16oz -- $3/can, can be found anywhere and everywhere. With the right fittings you can refill these from a larger bulk tank
> for less than 50 cents per pound.
>
> Coleman propane extension host -- $27, from Amazon
>
> Lindal valve to throwaway propane canister adapter -- $31, from Amazon.
>
> Yellow A/C charging hose -- I bought a full set of three hoses for $13 from Amazon.
>
> A gauge set is helpful, but not required.
>
> ------
>
> You'll need to cut the yellow charging hose, cut the Coleman propane extension hose, and join the two together with brass fittings and hose clamps.
> The prices for everything have gone through the roof these days so expect to spend $15-20 for the fittings. I recommend installing a brass shut-off
> valve, especially if you don't have a gauge set. If your coach has been converted to R134a you should have quick disconnect fittings installed on the
> factory 1/4" SAE schrader valves. In this case you will need a female R134a quick disconnect adapter to connect your charging hose. I recommend
> getting the 90* fittings with a shutoff valve built in. Uxcell sells some nice ones on Amazon for about $13 each.
>
> This guide assumes your A/C is already in basic working order; maybe low on charge, but with no major leaks or equipment failures. First start by
> evacuating the existing charge. I recommend venting the toxic DuPont crap into the atmosphere so it will never again have the opportunity to
> contaminate someone's A/C system. Otherwise if you feel it necessary for some reason, take it to an A/C shop and have them recover it.
>
> You will need to decide what ratio of propane/isobutane you want to run, and calculate the charge amount accordingly. It's said that 60/40
> propane/isobutane is the optimum ratio for drop-in R12/R134a replacement. This makes things simple, as if you charge the MSR IsoPro and Coleman
> propane in equal amounts, it will result in a 60/40 ratio. If the ratio is slightly off it doesn't matter. You can also experiment with different
> ratios depending on your desires, operating conditions, etc. People in extreme conditions and those wishing for better fuel economy/less compressor
> drag may want to run more isobutane; for better cooling per pound in normal climates use more propane. You can go as low as 20/80 propane/isobutane
> (using MSR IsoPro cans only; no Coleman fuel) or up to 75/25. The more propane you run, the higher system pressures will be, and the more load there
> will be on the compressor when it kicks in.
>
> When the system is empty, you can begin charging. It's pretty simple. Just charge it the same way you would any other refrigerant, except using your
> new spliced together charging hose. Be sure to bleed all air out of the hose(s) before charging. The early coaches use 3.5 pounds (56 oz) of R12, and
> the late ones (77-78 I think) use 3.75 (60 oz.) For optimum charge with hydrocarbons, use only 36% of the R12 total. That's 20.2 oz on early coaches,
> 21.6 on late models. The amount charged does not have to be exact; you can go an ounce or two over without hurting anything. Remember, if a 60/40
> ratio is desired, use equal amounts from the MSR IsoPro and Coleman propane. If other ratios are desired you will have to do some calculations to
> figure out the right amount to charge. Start your charging with the IsoPro first!! This way system pressures will start out low, and then will
> gradually increase as you charge in the propane. I recommend charging as a liquid by holding the can upside down, but be very careful to crack the
> valve open slowly and take your time with it so as not to accidentally slug the compressor by flooding it with liquid.
>
> When you've finished charging, you will have COLD A/C! My coach on a 95-100+ degree day has no problem icing up the evaporator with the cycling switch
> shorted to run the compressor constantly. It will easily blow 35* temps out of the vents like this, but of course, this isn't sustainable as the
> evaporator will completely ice over. With the compressor cycling normally, vent temps will hit 43-44* with the evaporator alternately icing and
> thawing. That's the best you're going to get out of a stock GMC with its terribly restrictive heater/AC box and vent design, with no insulation. There
> is much more refrigeration capacity than is actually able to be used due to this poor design. It's good enough however; at idle and driving down the
> road the A/C works great and feels comfortable even with no privacy curtain installed to keep the cold air up front.
>
> On a final note, some people make a big deal about the impurities present in camp fuel. It's true that camp fuel is not refined to the same degree as
> the base stock Duracool and other companies use. All propane sold in the USA is rated HD-5 which means it's at least 95% propane, with the majority of
> the rest being other hydrocarbon gases which are also themselves refrigerants and will not cause any problems. There may be a tiny bit of
> non-condensible gases in there, which isn't enough to harm anything, and won't be pulled into the system if you charge as a liquid. There is also
> likely to be a tiny bit of water vapor present, but again, this is harmless; your desiccant will absorb it quickly.
>
> What I love most about doing things this way is that the refrigerant is CHEAP. It costs a bit of money to buy the necessary adapters and fittings, but
> I don't care as I love to acquire new tools that expand my capabilities. Having bought the necessary tools, the total refrigerant cost to fill up a
> GMC is $15, or about $10 not counting the refrigerant that's left over to be used on other vehicles. At these prices I can afford to stockpile a large
> quantity of refrigerant to fill all of my vehicles and others' too for decades to come. With the right fittings for my bulk tank I can also refill the
> propane cans for less than 50 cents each, which makes the propane cost practically nothing. This is especially useful for charging R22 systems, which
> can be done basically for free. Kiss my ass DuPont!
>
> That pretty much covers it, but feel free to ask any questions you may have.
>
>
>
> --
> Gadsden, AL
>
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| Re: Charging dash A/C with hydrocarbons - alternate method [message #305072 is a reply to message #305055] |
Sun, 07 August 2016 16:17 |
gladius
Messages: 48
Registered: November 2015
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"Your write up makes me think that it is so much simpler to just buy 3 cans of Duracool (HC12a) for about $21 and fill with that. "
If that's what you want to do, then go ahead. Keep in mind you will need FOUR cans for the correct fill and it will cost you more like $36 + shipping. So about $48 by the time it gets to your door. If you only need to charge one vehicle one time I guess that's fine. I prefer to plan for the future also. If you ever need to recharge due to a leak, or want to charge multiple vehicles, by the time you've bought a two rounds of Duracool you'll be money ahead doing it my way. The cutting and splicing hoses is trivial; takes less than one minute from start to finish. There is no extra labor involved vs charging with a standard refrigerant. And as mentioned above, for $100-200 I can buy enough refrigerant to keep an entire fleet of vehicles charged up, for decades. Try that with Duracool. And when it comes to R22 systems, Duracool doesn't come anywhere close to the less than $1 per charge it takes to fill up with bulk propane.
[Updated on: Sun, 07 August 2016 16:30] Report message to a moderator |
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| Re: [GMCnet] Charging dash A/C with hydrocarbons - alternate method [message #305075 is a reply to message #305072] |
Sun, 07 August 2016 16:26 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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If you put in 4 cans the pressure will be way too high and it won't cool as well. My experience over many years shows that the GMC takes just a little under 3 six ounce cans.
You can do your method but I just don't have the time to tinker with it. I am retired now but my time is precious to me.
Emery Stora
77 Kingsley
Frederick, CO
> On Aug 7, 2016, at 3:17 PM, Nathan Cline wrote:
>
> "Your write up makes me think that it is so much simpler to just buy 3 cans of Duracool (HC12a) for about $21 and fill with that. "
>
> If that's what you want to do, then go ahead. Keep in mind you will need FOUR cans for the correct fill and it will cost you more like $36 + shipping.
> So about $45-50 by the time it gets to your door. If you only need to charge one vehicle one time I guess that's fine. I prefer to plan for the future
> also. If you ever need to recharge due to a leak, or want to charge multiple vehicles, by the time you've bought a few rounds of Duracool you'll be
> money ahead doing it my way. As mentioned above, For $100-200 I can buy enough refrigerant to keep an entire fleet of vehicles charged up, for
> decades. And when it comes to R22 systems, Duracool doesn't come anywhere close to the less than $1 per charge it takes to fill up with bulk propane.
> --
> Gadsden, AL
>
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| Re: Charging dash A/C with hydrocarbons - alternate method [message #305077 is a reply to message #305055] |
Sun, 07 August 2016 16:42 |
gladius
Messages: 48
Registered: November 2015
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"If you put in 4 cans the pressure will be way too high and it won't cool as well. My experience over many years shows that the GMC takes just a little under 3 six ounce cans."
For a proper charge with propane/isobutane you need 21-22 oz, which is 36% of the R12 charge. That's 3 full cans plus part of another. Mine is charged with about 24 oz and it works great. You may have been successful with only three cans, but I wouldn't risk it as undercharging can result in insufficient compressor oiling and will definitely have reduced cooling capacity. With the poor design of the GMC A/C system maybe you wouldn't notice any reduced cooling as the system can't use the full evaporator capacity anyway. This is beside the point, which is that doing it my way is cheaper if one is charging multiple systems, and it's not the least bit complicated to do.
"You can do your method but I just don't have the time to tinker with it. I am retired now but my time is precious to me. "
There isn't any tinkering involved. This is a straightforward and extremely simple job. It's no more complicated than charging with Duracool. All of the needed parts can be bought in one go off Amazon.com. If your time is too precious and you're loaded with money to burn then take your coach to a shop and pay them full price to do all of the work for you. If you can find one that will charge with hydrocarbons, of course.
I'm 33 years old and not retired--and not likely to ever be, if the current state of this country (that previous generations who failed to plan for the future are responsible for creating) is any indication. We are in the Great Depression 2.0, and I'm not wealthy. Saving money wherever I can and planning long term for future needs and potential hardship is important to me, just as it was for my great grandparents who survived the last Great Depression. The near future for America is World War 3, and there are hard times coming when many products (including refrigerant) will not be available at any price. That's why I insist on keeping stockpiles of important things, like refrigerant, so that I don't have to suffer like everyone else who expects to always be able to order stuff from across the country any time they need it.
[Updated on: Sun, 07 August 2016 16:56] Report message to a moderator |
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| Re: Charging dash A/C with hydrocarbons - alternate method [message #305079 is a reply to message #305073] |
Sun, 07 August 2016 17:01 |
A Hamilto
Messages: 4508
Registered: April 2011
Karma: 39
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gladius wrote on Sun, 07 August 2016 16:19"If you vent it into the atmosphere, DuPont gets to make and sell more of it for all the people out there that will continue using it."
That's their sin, not mine.
If it's charged into somebody else's A/C system it's going to end up leaking out eventually anyway, as volatile as the stuff is. You need to think about what I am saying. When you vent it into the atmosphere, DuPont gets more money. Why do you want DuPont to get more money by selling more of it? Let the clueless sheep use recycled R-134a bought from a local business instead of giving DuPont more money to make more.
You are benefitting DuPont when you vent it into the atmosphere instead of having it recovered for re-use.
If you can't see that, you are not very bright.
[Updated on: Sun, 07 August 2016 17:13] Report message to a moderator |
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| Re: Charging dash A/C with hydrocarbons - alternate method [message #305085 is a reply to message #305055] |
Sun, 07 August 2016 17:50 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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2.5 or 2.75 cans does a complete fill for me on every GMC that I have charged. If you are installing 3 or more then you are over charged and the system will not cool as well.
If I were to run out, I would simply take a trip to the local Duracool store and get some more or order frosty cool on line. It is not likely that I would be charging a bunch of cars since I only use Duracool as an r-12 replacement. On R-134 cars I use R-134. I have a 30 pound bottle that will last longer than I do.
It is a neat idea but not worth the investment or time for me to do it.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Charging dash A/C with hydrocarbons - alternate method [message #305133 is a reply to message #305055] |
Mon, 08 August 2016 11:08 |
gladius
Messages: 48
Registered: November 2015
Karma: 0
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"2.5 or 2.75 cans does a complete fill for me on every GMC that I have charged. If you are installing 3 or more then you are over charged and the system will not cool as well. "
Not to be pedantic, but it's important to get this correct. How are you measuring a "complete fill"? I assume the GM engineers knew what they were doing when they specified 56-60oz as the correct amount of R12 for these systems. And I also assume the engineers at Duracool are also correct when they state on their website:
"6 oz. cans (equivalent to 17 oz. CFC-12 / 15 oz. R-134a)"
6 / 17 = 35.3%, times 56 oz is 19.8oz, or times 60 oz is 21.2oz. Both of those numbers represent over three cans worth of Duracool. Just because the system starts cooling well as you fill it up doesn't mean it's full yet. If it's underfilled you might not have a problem with pump lubrication due to the excellent solubility of oil in hydrocarbons, but you will definitely decrease system cooling capacity. It's better to slightly overfill than to underfill. I used 36% in my calculations and I actually "overfilled" my system by about 2 ounces. It cools great, and could not possibly be better, within the constraints of the stock GMC design. The evaporator easily ices up at idle on a 95-100+ degree day.
[Updated on: Mon, 08 August 2016 11:13] Report message to a moderator |
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| Re: [GMCnet] Charging dash A/C with hydrocarbons - alternate method [message #305135 is a reply to message #305133] |
Mon, 08 August 2016 11:28 |
k2gkk
Messages: 4452
Registered: November 2009
Karma: -8
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Regardless of all the number throwing on this subject, I don't believe it to be a "good thing" when the evaporator ices up!
I believe the point being made by some is that 2.5 to 2.75 cans of the Duracool (or equivalent) has been found to be a "sweet spot" for efficient cooling without the freeze-up of the evaporator.
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
~~ ~ D C "Mac" Macdonald ~ ~~
~ ~ Amateur Radio - K2GKK ~ ~
~ ~ Since 30 November '53 ~ ~
~ ~ USAF and FAA, Retired ~ ~
~ Member GMCMI and Classics ~
~ ~ ~ Oklahoma City, OK ~ ~ ~
~~ ~ ~ "The Money Pit" ~ ~ ~~
~ ~ ~ ~ TZE166V101966 ~ ~ ~ ~
~ ~ ~ '76 ex-Palm Beach ~ ~ ~
~~ k2gkk + hotmail dot com ~~
~ www.gmcmhphotos.com/okclb ~
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
______________
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"--OO--[]---O-"
________________________________
From: Gmclist on behalf of Nathan Cline
Sent: Monday, August 8, 2016 11:08
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] Charging dash A/C with hydrocarbons - alternate method
"2.5 or 2.75 cans does a complete fill for me on every GMC that I have charged. If you are installing 3 or more then you are over charged and the
system will not cool as well. "
Not to be pedantic, but it's important to get this correct. How are you measuring a "complete fill"? I assume the GM engineers knew what they were
doing when they specified 56-60oz as the correct amount of R12 for these systems. And I also assume the engineers at Duracool are also correct when
they state on their website:
"6 oz. cans (equivalent to 17 oz. CFC-12 / 15 oz. R-134a)"
6 / 17 = 35.3%, times 56 oz is 19.8oz, or times 60 oz is 21.2oz. Both of those numbers represent over three cans worth of Duracool. Just because the
system starts cooling well as you fill cans doesn't mean it's full yet. If it's underfilled you might not have a problem with pump lubrication due to
the excellent solubility of oil in hydrocarbons, but you will definitely decrease system cooling capacity. It's better to overfill than to underfill.
I used 36% in my calculations and I actually "overfilled" my system by about 2 ounces. It cools great, and could not possibly be better, within the
constraints of the stock GMC design. The evaporator easily ices up at idle on a 95-100+ degree day.
If this way of doings things doesn't make any sense to someone, then use Duracool or some other product. I didn't take the time to write this up for
the naysayers or doubters, but for other experimenters and do-it-yourselfers who may find some value in it.
--
Gadsden, AL
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| Re: Charging dash A/C with hydrocarbons - alternate method [message #305140 is a reply to message #305131] |
Mon, 08 August 2016 11:56 |
A Hamilto
Messages: 4508
Registered: April 2011
Karma: 39
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Senior Member |
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gladius wrote on Mon, 08 August 2016 10:48...If I allow the refrigerant to be recovered, doesn't this theoretically help reduce the price of R134a on the used market as well, if the theory of supply and demand is to be believed, thus resulting in more sales of R134a to the public? ... No. There are two flaws in your argument. The first one being that supply and demand apply to this product. The number of devices that use it, and the quantity contained in each is independent of the price, unless/until it goes through the roof, which DuPont won't let happen (that would increase the potential for competition). Second, the price of the second-hand stuff is as high as newly produced, due to the cost to recover and profit drive of the shop.
Any way you try to justify it to yourself, venting it into the atmosphere results in more being produced. If you want less to be produced, do what you can to keep what is already in existence contained.
None of this takes away from my support of your process for making HC-based refrigerants less expensive and for explain how to make the tools for implementation.
All I object to is the idea that venting the DuPont produced poison into the atmosphere does anything but generate more profit for DuPont. That's all it can do, so stop arguing with me.
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| Re: [GMCnet] Charging dash A/C with hydrocarbons - alternate method [message #305142 is a reply to message #305133] |
Mon, 08 August 2016 11:50 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Senior Member |
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Yes, good choice of words. You are being very "pendatic".
You cannot put blind faith into the 36% number on the Duracool website. I spoke to the Duracool tech people many years back and they told me that percentage was just a guideline. Some systems take more and some systems less. Smaller systems seem to take more.
It was on their advice that I reduced the percentage for the GMC motor home.
It was from empirical evidence with over 100 installations that I have done that determined that slightly less than three cans gave the desired pressure in the system.
With Duracool overfilling will result in higher temperatures. Under filling will give too much cooling and result in icing of the evaporator which blocks airflow.
I believe you are one of those with a closed mind that will not listen to anyone with experience in a subject so I will no longer waste my time responding to your postings.
Readers can decide for themselves what or who to believe.
Emery Stora
77 Kingsley
Frederick, CO
> On Aug 8, 2016, at 10:08 AM, Nathan Cline wrote:
>
> "2.5 or 2.75 cans does a complete fill for me on every GMC that I have charged. If you are installing 3 or more then you are over charged and the
> system will not cool as well. "
>
> Not to be pedantic, but it's important to get this correct. How are you measuring a "complete fill"? I assume the GM engineers knew what they were
> doing when they specified 56-60oz as the correct amount of R12 for these systems. And I also assume the engineers at Duracool are also correct when
> they state on their website:
>
> "6 oz. cans (equivalent to 17 oz. CFC-12 / 15 oz. R-134a)"
>
> 6 / 17 = 35.3%, times 56 oz is 19.8oz, or times 60 oz is 21.2oz. Both of those numbers represent over three cans worth of Duracool. Just because the
> system starts cooling well as you fill cans doesn't mean it's full yet. If it's underfilled you might not have a problem with pump lubrication due to
> the excellent solubility of oil in hydrocarbons, but you will definitely decrease system cooling capacity. It's better to overfill than to underfill.
> I used 36% in my calculations and I actually "overfilled" my system by about 2 ounces. It cools great, and could not possibly be better, within the
> constraints of the stock GMC design. The evaporator easily ices up at idle on a 95-100+ degree day.
>
> If this way of doings things doesn't make any sense to someone, then use Duracool or some other product. I didn't take the time to write this up for
> the naysayers or doubters, but for other experimenters and do-it-yourselfers who may find some value in it.
> --
> Gadsden, AL
>
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