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A/C question

 
Old 02-04-2019, 07:24 PM
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jagvette
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OK, so I have an 88 C4 and of course the A/C doesn't work and the system was the old R12, I am going to convert it to R134A and need to know how much R134a I need and are there items I MUST replace.

and just to kiss *** I KNOW YOU GUYS/GIRLS can help
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Old 02-04-2019, 07:28 PM
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You'll need to investigate the details, but my understanding is that there is a direct (and cheap) R12 replacement with no changes to the system.
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Old 02-04-2019, 09:54 PM
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I put in 3 12 oz cans and +6 ounces of r134 into my conversion. But it won't take it unless a vacuum is pulled. Which you really should do for 45 min anyways to evac the system.

Still working after 1 1/2 years.
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Old 02-04-2019, 10:20 PM
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raya123_2000
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I changed my system to R134A about 5 years ago it's been working great I had my compressor rebuilt, then I just flushed out the system real good. The auto parts places will rent the gear you need. You must change out the dryer, the schrader valves and the orifice (expansion valve). The orifice has different colors which have different size openings. The smaller the opening the colder the A/C will be.

You have to evacuate the system and leave it in place over night to verify no leaks. My 1990 Vette would set a ECM error of low refrigerant that has to be cleared before the compressor will run. I found that the gauge set from the auto parts place barley work so I just added R134A till the compressor would stay running the determined my vent temp by how hot it was out side. It still working.

The way I filled it was with a thermometer in the AC vent (meat thermometer works best). You then add refrigerate until the correct temperature appears on the thermometer. There is a chart on the internet that tells you how to make this measurement. You check the temperature at the condenser and that will tell you how cold the thermometer will go. you have to add more R134A than the old refrigerant.

Ray
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Old 02-05-2019, 04:37 AM
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You might also add a little yellow leak detector fluid if not included in the R134A used.
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Old 02-05-2019, 07:46 AM
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You'll want to replace the receiver/dryer and install the new fittings. A good 15 or so minute vacuum on the system with an a/c machine will help to remove all of the R12. After that you'll need 2 pounds 12 ounces of R-134 and 1 ounce of oil.
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Old 02-05-2019, 09:29 AM
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This stuff goes in the stock system with no extra modification:

http://www.redtek.com/products_refr.html

Blowing cold and working great on two different cars after 6+ months (3 during the summer). Once it gets hot again I'll let you know if it's still going, but honestly a can to recharge every year isn't a big deal to me.
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Old 02-05-2019, 02:45 PM
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Originally Posted by jagvette View Post
OK, so I have an 88 C4 and of course the A/C doesn't work and the system was the old R12, I am going to convert it to R134A and need to know how much R134a I need and are there items I MUST replace.

and just to kiss *** I KNOW YOU GUYS/GIRLS can help
If R12 was available, I'd go that way even if it is a little more. I have R134A and we were never able to get it as cool as R12 on the hot and humid days in stop and go traffic. Nobody I talked to has been able to say that it works AS WELL AS the old R12 in hot humid weather.

What are you changing? Compressor and Receiver/Dryer at the least. You have to change all the O-rings. I changed all the hoses too. I'd flush it but I would never fill it in my garage. That I get a shop with the right equipment to do.
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Old 02-06-2019, 03:19 AM
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The Thomas J
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I agree. My R12 setup was colder. A couple of years ago I bought a bunch of cans at a swap meet. Worth every penny. I would still have that setup if my compressor had not blown up.
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Old 02-06-2019, 09:19 AM
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I still recommend the Redtek product. Guy I bought my car from had it recharged with r134a and complained it didn't work. I was worried something might have been ruined but I just vacuumed the system and added the Redtek, and it's still going strong. I tested in 70 degree weather yesterday and it was cold as ice.
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Old 02-06-2019, 10:55 AM
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Originally Posted by jagvette View Post
OK, so I have an 88 C4 and of course the A/C doesn't work and the system was the old R12, I am going to convert it to R134A and need to know how much R134a I need and are there items I MUST replace.

and just to kiss *** I KNOW YOU GUYS/GIRLS can help
for the conversion, you need, obviously, the high pressure/low pressure port adapters to charge the system, and R134a compatible O-rings. you should install a NEW accumulator/dryer, drain the compressor, and i'd flush the entire system. ideally, it would be nice to install a new compressor, but in your case, that's a big ticket item, so drain and flush at a minimum. the oil used with R12 is not compatible with PAG oil used in a R134a system. i'd switch to ester oil which is compatible with both systems. my understanding is you should try to get 95% of the old oil out of the system, which is why you should flush the system. replace the orifice tube, and I recommend going with a .067 vs (i'm thinking) the stock .072 orifice tube. you will also need to replace the low pressure cycling switch. a functioning R134a system will use approximately 85% of the freon required in a R12 system, however, it all pressure related and dependent. tools and equipment, you'll need a vacuum pump, and a manifold/gauge set.

I converted my 85's R12 system to R134a close to 3 years ago, new compressor, accumulator/dryer, orifice tube, cycling switch, etc. I did it by the book -- no regrets. still working without issues. center duct temps around 40 at cruise, and around 55 in stop and go traffic. these temps are with 90 summer days here in florida. if you're serious about the conversion, start here...


then again, there are folks that have had success with the $39 Wal-Mart, conversion in a can method too -- depends on how you want to go about it.

Last edited by Joe C; 02-06-2019 at 10:56 AM.
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Old 02-06-2019, 11:36 AM
  #12  
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Originally Posted by Joe C View Post
for the conversion, you need, obviously, the high pressure/low pressure port adapters to charge the system, and R134a compatible O-rings. you should install a NEW accumulator/dryer, drain the compressor, and i'd flush the entire system. ideally, it would be nice to install a new compressor, but in your case, that's a big ticket item, so drain and flush at a minimum. the oil used with R12 is not compatible with PAG oil used in a R134a system. i'd switch to ester oil which is compatible with both systems. my understanding is you should try to get 95% of the old oil out of the system, which is why you should flush the system. replace the orifice tube, and I recommend going with a .067 vs (i'm thinking) the stock .072 orifice tube. you will also need to replace the low pressure cycling switch. a functioning R134a system will use approximately 85% of the freon required in a R12 system, however, it all pressure related and dependent. tools and equipment, you'll need a vacuum pump, and a manifold/gauge set.

I converted my 85's R12 system to R134a close to 3 years ago, new compressor, accumulator/dryer, orifice tube, cycling switch, etc. I did it by the book -- no regrets. still working without issues. center duct temps around 40 at cruise, and around 55 in stop and go traffic. these temps are with 90 summer days here in florida. if you're serious about the conversion, start here...


then again, there are folks that have had success with the $39 Wal-Mart, conversion in a can method too -- depends on how you want to go about it.
How did you do the switchs? I had to scrounge for NOS since they did not have it at FJC
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Old 02-06-2019, 02:02 PM
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Joe C
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Originally Posted by aklim View Post
How did you do the switchs? I had to scrounge for NOS since they did not have it at FJC
what switches? low pressure cycling switch? bought an FJC assembly on fleabay. the low pressure switch is the only one I replaced

Last edited by Joe C; 02-06-2019 at 02:02 PM.
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Old 02-06-2019, 10:04 PM
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Originally Posted by jagvette View Post
OK, so I have an 88 C4 and of course the A/C doesn't work and the system was the old R12, I am going to convert it to R134A and need to know how much R134a I need and are there items I MUST replace.

and just to kiss *** I KNOW YOU GUYS/GIRLS can help
just a follow up - before you start, it would be nice to know why your original R12 system failed. was it a simple O-ring, or did you have a major component failure? I've read that its not uncommon to loose approximately one pound of Freon per year, but in my book, that would be unacceptable. so, do you just need an R12 recharge or are there other, more serious issues? in my case, I was looking at a compressor (bearing) failure. I didn't want to fool with the R12 anymore, even though I had four 12-ounce cans on hand. I found it was cheaper in my case to install a new compressor than to rebuild my original - parts, plus I would have had to buy some specialized tools. anytime you open the system to atmosphere, you should replace the accumulator/dryer. this is no big deal since replacements are fairly inexpensive. with everything going on with my 85's AC system, it just made good sense to convert. again, no regrets. .
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Old 02-08-2019, 11:06 AM
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Mine was r134 when I bought it. Needed some refrigerant last year. The R134 works fine and gets plenty cold.
These were taken after work. Took about 3 miles in light city traffic to achieve these temps.

Outside

dash vent at starup

final output temp
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Old 02-08-2019, 11:16 AM
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Originally Posted by belairbrian View Post
Mine was r134 when I bought it. Needed some refrigerant last year. The R134 works fine and gets plenty cold.
These were taken after work. Took about 3 miles in light city traffic to achieve these temps.

Outside

dash vent at starup

final output temp
38 --
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Old 02-08-2019, 08:13 PM
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Originally Posted by aklim View Post
You have to change all the O-rings. I changed all the hoses too. I'd flush it but I would never fill it in my garage. That I get a shop with the right equipment to do.
I have heard people say this before, change all O-rings. I have also read that it's OK to leave any O-rings that are not leaking, but replace the ones on anything you open. I have always done the latter with success. Changeed the ones like on the dryer, and compressor (if I replaced or removed it) but left others alone unless it was leaking from them, Has worked out on all the cars I've done a conversion to.
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Old 02-08-2019, 08:47 PM
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Originally Posted by gpierce View Post
I have heard people say this before, change all O-rings. I have also read that it's OK to leave any O-rings that are not leaking, but replace the ones on anything you open. I have always done the latter with success. Changeed the ones like on the dryer, and compressor (if I replaced or removed it) but left others alone unless it was leaking from them, Has worked out on all the cars I've done a conversion to.
Problem is those O-rings MAY NOT be R134a compatible. It increases the risk of leaks. Now if you have an increase in cost by a couple of thousand dollars, you MAY think it would be an acceptable risk. If you get away with it, sure. If not and you have to go in and do it again, is it worth it? Not to me. You may be more able to absorb the risk of failure and not mind going in again.
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