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Recharging the Air Conditioner R134

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Old 05-28-2009, 01:04 PM
  #21  
SunCr
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Not what we're after:

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Old 05-28-2009, 02:19 PM
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thats funny!!!!!!!!!!!what a butch
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Old 05-28-2009, 02:28 PM
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Originally Posted by coupeguy2001 View Post
ok, now my way. i didn't evacuate the system, I took the car to a place that I had work done on my old compressor. The guy said honestly, he couldn't tell any difference if he evacuated all the oil out or just added. He said just put your new compressor on, and it will be ok. He said if anything is damaged, he would fix it for free. he told me to go to auto zone or checker, and buy one of those conversion kits, and just put in the oil (pag oil) and add 2 cans of freon, he preoiled the repaired compressor, and sent me on my way. In retrospect, he figured that with 8% humidity, it would be ok.
That was 4 years ago. I have added a couple cans of freon because the compressor as of late is showing signs of oil residue, indicating the seals are once again leaking after about 23,000 miles. It still blows 45 degree air, and cools fine. Sometimes it's 118 degrees outside, so I guess 23,000 miles in that kind of abuse is ok.
unbelievable......really.

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Old 05-28-2009, 02:42 PM
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Okay,,,, if you install a new compressor, new lines, new accumulator and new front coil and then take it to a shop to have the sytem checked for leaks, vacumed and charged with R134, what might be the ball park cost to do it this way?
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Old 05-28-2009, 02:44 PM
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Originally Posted by MikeC4 View Post
Once you have converted your hardware over to R134, these vids on evacuating and re-charging might be of some help:
Good overview. Thanks
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Old 05-28-2009, 08:02 PM
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Originally Posted by pmihaltian View Post
Okay,,,, if you install a new compressor, new lines, new accumulator and new front coil and then take it to a shop to have the sytem checked for leaks, vacumed and charged with R134, what might be the ball park cost to do it this way?
My guesstimate:
Your looking at about $1,000 in parts and $200 labor for leak check/evac/re-charge.

I am assuming you mean that "you" are going to install the new AC components, and not the shop.

The heavy hitter here is the rebuilt compressor, which is going to run you about $500

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Old 05-28-2009, 10:05 PM
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Doing all the parts and adding the oil along the way means your looking at 20 minutes to pump it down; 10 minutes to fill it up and a couple of pounds of gas (about $8/lb retail for R134; $25 to $30/lb for R12). Anything more than $125 for an R134 fill is way too much. The last time I dropped by a shop (it's been about 10 years now), the guy did it for free - then told me the Evaporator was leaking and wanted $800 to replace it. I offered him 50 Bucks for his trouble (which amazingly he declined) and let him have his gas back. Check around - there's a lot of hungry/unemployed people out there.
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Old 05-28-2009, 10:44 PM
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Originally Posted by SunCr View Post
Doing all the parts and adding the oil along the way means your looking at 20 minutes to pump it down; 10 minutes to fill it up and a couple of pounds of gas (about $8/lb retail for R134; $25 to $30/lb for R12). Anything more than $125 for an R134 fill is way too much. The last time I dropped by a shop (it's been about 10 years now), the guy did it for free - then told me the Evaporator was leaking and wanted $800 to replace it. I offered him 50 Bucks for his trouble (which amazingly he declined) and let him have his gas back. Check around - there's a lot of hungry/unemployed people out there.
SunCr :
I have a 2.5 CFM vacuum pump for drawing down my car AC units. I typically pump down the system for about 30 minutes, shut the pump off for about 10 minutes or so to ensure that vauum is maintained, then turn the vacuum pump on for an additional 30 minutes.

Do you think this procedure is adequate w/ 2.5 CFM pump ?
What is typical CFM rating of the pumps used by the "pros" ????

Thanks,
Mike
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Old 05-29-2009, 12:41 AM
  #29  
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You can never over do it . I have a vacumm guage that lets you see the actual vacumm in microns. I have a six cfm pump and it takes about 20 minute to reach 500 microns. And yes suncr I have more than 608 I have universal epa/imaca for automobile / NATE and so on..I was comparing the pressure temperature relations of hot shot, r-12, r-134a and @ 40 degrees the pressures of hotshot 31.1, r-12 36.9,134a 35 looked promising for hot shot ,but when you go to high pressure @ 100 degrees hotshot 138, r-12 116.9, 134a 124.2. So r-12 is the best one but 134a is not to far behind. Hotshot way to much of a difference..
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Old 05-29-2009, 12:45 AM
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mikec4 2.5cfm is good.And stopping between is a good way to tell if you have leaks.
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Old 05-29-2009, 10:05 AM
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You don't indicate your location, so we don't know what climate you live in. This is important data when it comes to A/C and a Vette. I'm in Texas, so my car has an auxialliary fan and shrouding that makes the system more effective.

In cooler climates, the a/c guys say that these cars are notorious for their low performance a/c. For this reason, you will be MUCH better served staying with R12. It is more expensive, but you will in the long run spend more money on a converted system. BTDT!

If I were doing your a/c I would start by evacuating the system to see if it would hold a vacuum overnight. I would turn the compressor by hand to see if it is making compression and turns smoothly. If the system passed that part of the test I would replace the accumulator, check the orifice tube and recheck for leaks, add several ounces of mineral oil beyond the 3.5 ounces that the new accumulator needs, evacuate and charge with R12.

If the system didn't pass the initial test, fix the leaks, replace the compressor or whatever it takes. If you have to replace the compressor, break EVERY connection and THOROUGHLY flush ALL components in the system to remove the debris that was left behind by the failed compressor.

If you choose to ignore recommendations to stay with R12 and convert to 134, then you should flush all lines and components, fill with 8 ounces of Ester oil and charge the system BY WEIGHT. Start with 30 ounces which will be 70% of the R12 spec. Drive the car at that point with a vent thermometer to monitor performance. If it is not making good vent temp, add one ounce of 134 at a time and don't let the high side pressure go over about 250 or 260.

Good luck with it,
Doc
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Old 05-29-2009, 03:23 PM
  #32  
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i agree with MB stay with the r-12,,,,,,and honestly hot shot is a real good option,,its readily avail. and any refrigeration repair tech should have this on their truck,,,i know i do and have charged many a/c systems with it,,,just make sure the guy doing it for u is SECTION 609 EPA CERT. ,,,UNIVERSIAL CERT SECTION 608 DOES NOT ALLOW FOR AUTO A/C REPAIR....TWIN 540 YOU SHOULD KNOW THAT.
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Old 06-03-2009, 10:20 AM
  #33  
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You guys are GREAT ! Thank you for keeping me straight and pointing me in the right direction.

Since I first asked this question my AC has stopped working altogether. I had DarkBlue 88 come over and check it out for me and he spotted a blown hose right away. Sooooo, I am going to replace the hose, replace the accumulator and test the system for leaks. If it will hold pressure, I am going to recharge with R12 and be on my way. If, not, I am going to rebuild compressor and replace the front coil and them recharge with R12. That's my plan.

Thanks again.
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Old 06-03-2009, 10:39 AM
  #34  
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Originally Posted by pmihaltian View Post
You guys are GREAT ! Thank you for keeping me straight and pointing me in the right direction.

Since I first asked this question my AC has stopped working altogether. I had DarkBlue 88 come over and check it out for me and he spotted a blown hose right away. Sooooo, I am going to replace the hose, replace the accumulator and test the system for leaks. If it will hold pressure, I am going to recharge with R12 and be on my way. If, not, I am going to rebuild compressor and replace the front coil and them recharge with R12. That's my plan.

Thanks again.
I am curious, did you get a quote on how much it will cost for an R12 recharge ?? I heard this stuff has gotten real expensive ?

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Old 06-03-2009, 10:56 AM
  #35  
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Originally Posted by MikeC4 View Post
I am curious, did you get a quote on how much it will cost for an R12 recharge ?? I heard this stuff has gotten real expensive ?

DarkBlue 88 is a GM A/C Master Tech and he told me that R12 is readily available at most auto parts stores in the Charlotte area for about $30 for a 12 oz can. He said that you have to have a license to buy it, but it is available. He indicated that we will probably need 3 cans for a complete recharge. So, I;m thinking $90 for gas and another $100 - $125 to vacuum the system and recharge it.
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Old 06-03-2009, 12:21 PM
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Originally Posted by coupeguy2001 View Post
ok, now my way. i didn't evacuate the system, I took the car to a place that I had work done on my old compressor. The guy said honestly, he couldn't tell any difference if he evacuated all the oil out or just added. He said just put your new compressor on, and it will be ok. He said if anything is damaged, he would fix it for free. he told me to go to auto zone or checker, and buy one of those conversion kits, and just put in the oil (pag oil) and add 2 cans of freon, he preoiled the repaired compressor, and sent me on my way. In retrospect, he figured that with 8% humidity, it would be ok.
That was 4 years ago. I have added a couple cans of freon because the compressor as of late is showing signs of oil residue, indicating the seals are once again leaking after about 23,000 miles. It still blows 45 degree air, and cools fine. Sometimes it's 118 degrees outside, so I guess 23,000 miles in that kind of abuse is ok.


OP, all these guys are telling you the truth..........that being said....how much do you want to spend on a car that is worth $4000??

What Coupguy said is true as well....fill it with the $50 kit from Kragen and drive off into the sunset.....

Will this give you 100k mile service??? probably not....but are you going to get another 100k out of that car??

If it makes you feel better, fill and purge a few times......Fill it up, run it for a while and then let it out......Fill it again. Two cans are your only cost for this method....and if you have a leak....aren't you going to be "autopurging" over time anyway???

I do understand why most of the replies are so in depth with replacing this and that...but I have to bring a practical side to the thread. spending $1000 bux to "do it right" will give you another 100k miles service and that is what a "shop" should be doing for the money they charge....

But sometimes a $50 kit that takes 15 minutes to install and fill is just as attractive.....I did mine at 60k miles (yes on an '84 back in '06) and I'm now at 90k miles....Yes I had to put in another can......but it blows cold...nice and cold.....frigid almost.

Not to mention, I did it to my old RX7 and also my Celica......I put about 50k on an old car and then sell it....so three cars with "no A/C" fixed for the price of that kit I found in ~'03

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Old 06-03-2009, 12:41 PM
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Originally Posted by jhammons01 View Post


OP, all these guys are telling you the truth..........that being said....how much do you want to spend on a car that is worth $4000??

What Coupguy said is true as well....fill it with the $50 kit from Kragen and drive off into the sunset.....

Will this give you 100k mile service??? probably not....but are you going to get another 100k out of that car??

If it makes you feel better, fill and purge a few times......Fill it up, run it for a while and then let it out......Fill it again. Two cans are your only cost for this method....and if you have a leak....aren't you going to be "autopurging" over time anyway???

I do understand why most of the replies are so in depth with replacing this and that...but I have to bring a practical side to the thread. spending $1000 bux to "do it right" will give you another 100k miles service and that is what a "shop" should be doing for the money they charge....

But sometimes a $50 kit that takes 15 minutes to install and fill is just as attractive.....I did mine at 60k miles (yes on an '84 back in '06) and I'm now at 90k miles....Yes I had to put in another can......but it blows cold...nice and cold.....frigid almost.

Not to mention, I did it to my old RX7 and also my Celica......I put about 50k on an old car and then sell it....so three cars with "no A/C" fixed for the price of that kit I found in ~'03
John, there is certainly merit in your logic of "car value" versus "AC cost of repair". My only "Huh?" in your methodology is the cost of "fill and purge" for an R12 system can be pretty dayum costly. $30 for R12 vs. $7 R134a is a compelling argument to switch over...IMHO

The caveat being the car will be kept for a few or more years...

friggin' AC....can't live with it, can't live without it

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Old 06-03-2009, 12:56 PM
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No no on the R12 fill and purge.....Fluorocarbons are bad...

But 134a is free of nasty stuff......and those smaller cans fluctuate between $3 and $10....depending on whatever drives that market...I've never figure it out and as you can see...I am buying it every now and again.

So two cans @ an average of $6...you've purged for $12 bucks....and you only need to purge it twice...at first.....but then after if you have a leak then you are only refilling.....positive pressure keeps the moisture from permeating into the system so no purge needed again......

And I'm not saying you have to purge....if the systems hoses were never broken open then why purge?? if you just allowed the gas to seep out via the schreader valves then there will not be a need to purge

The purge method I have adopted from the Cryogenic industry that uses the same compressor with pure Helium to reach temps as low as 4 Kelvin.

OH MikeC4, I get that purge procedure from your area!! Austin Scientific.....just off of I-35

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Old 06-03-2009, 01:25 PM
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Originally Posted by jhammons01 View Post
No no on the R12 fill and purge.....Fluorocarbons are bad...

But 134a is free of nasty stuff......and those smaller cans fluctuate between $3 and $10....depending on whatever drives that market...I've never figure it out and as you can see...I am buying it every now and again.

So two cans @ an average of $6...you've purged for $12 bucks....and you only need to purge it twice...at first.....but then after if you have a leak then you are only refilling.....positive pressure keeps the moisture from permeating into the system so no purge needed again......

And I'm not saying you have to purge....if the systems hoses were never broken open then why purge?? if you just allowed the gas to seep out via the schreader valves then there will not be a need to purge

The purge method I have adopted from the Cryogenic industry that uses the same compressor with pure Helium to reach temps as low as 4 Kelvin.

OH MikeC4, I get that purge procedure from your area!! Austin Scientific.....just off of I-35
Yikes....I guess a conversion to Cryo-cooling would be overkill in our vettes !!



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Old 06-03-2009, 02:54 PM
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Just a bit LOL......

No, we don't need such a volatile gas as Helium....134a works just fine.....any cooler than what we get now would lead to a block of ice forming and no air getting through.

those temps are used to create vacuum levels of 10-10 torr......or greater....(the surface plate is so cold that the molecules stick to it while they are bouncing around.....just like condesation only with Hydrogen etc......

They take regulate A/C compressors and "soup" them up to handle the lighter molecule of helium along with the greater heat created upon compression.....and then they circulate the compressed helium to a "cold finger" or "cold plate" where the gas being allowed to expand (just like our a/c system) and the cooling effect takes place.

Some make a big deal out of it...but we've had closed loop compressor systems in use for over 100 years...there aint much "new" about it....
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