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Old 07-27-2014, 04:44 PM   #1
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R22 vs. R134A


So half of you are going to chew my butt out for even trying this and the other half are going to laugh your butt's off for me even trying this. But I need an answer. About two years ago the A/C unit on my camper quit blowing cold air. A good inspection and I find a tiny pin hole in one of the 180 degree bends on the condenser. Figuring that if there is this one pinhole then there are others just waiting to happen so I buy a new unit. Actually I also upgraded from a 13,500 BTU unit to a 15,000 BTU unit and all has been well. So now my son comes into the picture wanting to know what I am going to do with the old unit I have not bothered to get rid of. He want's to see if we can get it working and he will put it on his little work shop at his house. Heck, let's just try it. So I reach back to my HVAC classes of 1969 and go from there. Patching the leak is no problem just solder a patch over the pinhole and that goes well. Now we do have a problem-the old unit used R22 refrigerant which is nowhere to be found. So why can't we use R134A I ask? I do a little research and find out that some systems can be converted from R22 to R134 with some O-ring changes and other part changes. Well, let's not get that deep into this unit. I strategically place a new saddle valve (I hear the groans now) on the suction line, place the adapter on this so I can use my R134 gauges and hook up my trusty old vacuum pump made from a Ford A/C compressor. I draw a good -33 vacuum on this unit for a couple of hours the shut the vacuum pump down. Now let's see of it holds a vacuum. Yeppers it held overnight so things look promising. Now this unit states that it need 15 oz. of R22 and the cans I have of R134 are 12 oz. cans. Being as I have now way of weighing any amount that small, I sold those scales year ago when I quit smoking that stuff, I just used the SWAG system. I put one whole can in and guessed at the three (3) oz. The low pressure gauge has a reading of 25 p.s.i. which I think is good. Hey, the unit was running fine and sounded really good, BUT--the air coming from the unit is not really cold, at all, not really. I check it with two thermometers and both of them had it at 80 degrees. Now in my shop that felt pretty good, but that's not the temp I wanted. Water is running from the tray of the evaporator because the humidity is high in the shop so that part seems to be working but the air coming from the unit just isn't cold. Now--could this be due to this unit being designed to run R22 and I'm trying to get it to run on RT134?

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Old 07-27-2014, 06:40 PM   #2
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R22 vs. R134A


Yep. R22 requires a larger volume of refrigerant flow then R134A. So you now have to large of a metering device for R134A.

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Old 07-27-2014, 08:36 PM   #3
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R22 vs. R134A


we still buy r-22 for about 249.00 for 30 pounds....not sure why you say it nowhere to be found......
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Old 07-27-2014, 08:41 PM   #4
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R22 vs. R134A


"beenthere"- -I do appreciate that info even though I don't know what that means. I'm not going to tear into this system to change anything I do know that much. I hate to admit this but I was sitting in the house later talking to myself about this unit and my girl friend heard me. She asked "would the temperature in the shop have anything to do with the air not feeling cold enough".Bing--a bell rang in my head. Heck NO I wouldn't admit to here that had something to do with it but I knew it did. The temp in my shop was in the high 80's when I had the unit running and I was expecting the air temp from the unit to be in the low 70's. It just ain't gonna happen. I went out later to check with a thermometer and the shop temp was 88, the air from the unit was 80. So maybe that wouldn't be so bad if the unit was exchanging air from a closed room.
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Old 07-27-2014, 08:51 PM   #5
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R22 vs. R134A


What type of metering device does the unit use? If it's a cap tube you can try carefully, and slowly crimping the cap tube in one spot to cause a greater restriction for the R-134A assuming that's what the system wants for the switch. Remember to crimp slightly and wait a while before making any judgments. Our members on the MT forum use a pinchoff tool for this.

http://weldwarehouse.com/cgi-bin/ein...H:1:389=105-FF

Before soldering that hole shut please tell me you will be flowing some nitrogen through the system first to push any air out?
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Old 07-27-2014, 09:34 PM   #6
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R22 vs. R134A


I'm not sure that it matters in your case but be aware that R134a uses PAG oil and R22 is mineral oil I think. Don't use any R134a cans that has oil mixed in with it.
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Old 07-28-2014, 04:40 AM   #7
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Quote:
Originally Posted by Thurman View Post
"beenthere"- -I do appreciate that info even though I don't know what that means. I'm not going to tear into this system to change anything I do know that much. I hate to admit this but I was sitting in the house later talking to myself about this unit and my girl friend heard me. She asked "would the temperature in the shop have anything to do with the air not feeling cold enough".Bing--a bell rang in my head. Heck NO I wouldn't admit to here that had something to do with it but I knew it did. The temp in my shop was in the high 80's when I had the unit running and I was expecting the air temp from the unit to be in the low 70's. It just ain't gonna happen. I went out later to check with a thermometer and the shop temp was 88, the air from the unit was 80. So maybe that wouldn't be so bad if the unit was exchanging air from a closed room.
The shop being 88 doesn't matter. The air is suppose to be much colder. just get someone to charge it with R22.

I'm down to my last 9 bottles of R22. I'll have to get another skid of it soon.
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Old 07-28-2014, 09:07 AM   #8
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"ben"- -I'm referring to the small can's of the old R22, "Freeze 12" type refrigerant. I have no use for one of the 30 pound cylinders but Thanks for the advice. "cj133- -as I said, I took HVAC class back in 1969 and have forgotten more than I can remember. Please don't give me a test and ask me to identify a "cap" tube. These RV units are strange animals. "beenthere"- -that is what I told my son he will need to do if he wants this unit now. I know someone who has an auto A/C shop. Keith would draw out the R134 from this unit, probably pull another vacuum on it again, maybe add some oil and charge it with R22 which he still has the 30# cans. This is one of those situations where "Hey, if we can get it to work fine, if we can't get it to work we're out nothing but time and experience". Thanks guys
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Old 07-28-2014, 09:17 AM   #9
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Quote:
Originally Posted by Thurman View Post
"ben"- -I'm referring to the small can's of the old R22, "Freeze 12" type refrigerant. I have no use for one of the 30 pound cylinders but Thanks for the advice. "cj133- -as I said, I took HVAC class back in 1969 and have forgotten more than I can remember. Please don't give me a test and ask me to identify a "cap" tube. These RV units are strange animals. "beenthere"- -that is what I told my son he will need to do if he wants this unit now. I know someone who has an auto A/C shop. Keith would draw out the R134 from this unit, probably pull another vacuum on it again, maybe add some oil and charge it with R22 which he still has the 30# cans. This is one of those situations where "Hey, if we can get it to work fine, if we can't get it to work we're out nothing but time and experience". Thanks guys

R12 and R22 are NOT the same thing, at all.

A capillary tube is a very thin, long copper tube often spooled up in one area. I was by no means giving a test, I'm giving suggestions, whether or not you can do the work is up to you.

Do you have a quality vacuum pump?



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Last edited by cj133; 07-28-2014 at 09:21 AM.
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Old 07-29-2014, 01:51 PM   #10
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R22 vs. R134A


Quote:
Originally Posted by Thurman View Post
"ben"- -I'm referring to the small can's of the old R22, "Freeze 12" type refrigerant. I have no use for one of the 30 pound cylinders but Thanks for the advice. "cj133- -as I said, I took HVAC class back in 1969 and have forgotten more than I can remember. Please don't give me a test and ask me to identify a "cap" tube. These RV units are strange animals. "beenthere"- -that is what I told my son he will need to do if he wants this unit now. I know someone who has an auto A/C shop. Keith would draw out the R134 from this unit, probably pull another vacuum on it again, maybe add some oil and charge it with R22 which he still has the 30# cans. This is one of those situations where "Hey, if we can get it to work fine, if we can't get it to work we're out nothing but time and experience". Thanks guys

True but make sure you ask him if he is going to charge you for the r22, street rate is between 50-75, so is he willing to up you a free pound?

Just asking!
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Old 07-29-2014, 05:19 PM   #11
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R22 vs. R134A


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Yep. R22 requires a larger volume of refrigerant flow then R134A. So you now have to large of a metering device for R134A.
isn't that stuff fun

Last edited by trapnfish; 07-29-2014 at 05:25 PM.
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Old 07-29-2014, 05:41 PM   #12
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isn't that stuff fun
R22 is a very forgiving refrigerant.
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Old 07-30-2014, 12:16 PM   #13
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"cj133": I do appreciate your suggestions. This RV A/C unit does not have the small tube shaped up into a spiral. But there is one small tube, maybe 1/8", that comes from the high side tubing and goes back into the evaporator. This may be the cap tube. I'm not sure I would be comfortable with trying to clamp/close this small tube using the SWAG system. Actually I do have a very good vacuum pump in addition to the old pump made from a Ford A/C compressor. I used the old school vacuum pump on this one just to see if it still worked and it did. "digitalplumber": As many favors as Keith owes me for doing work on his house--he danged well better not charge me for changing out the freon on this unit. That is IF I go to the trouble to go all this. As far as this stuff being fun--it really is. I love a challenge and enjoyed working on this unit. The unit is now in the possession of my son and as he drove away with it I thought of an old Roy Clark song: Thank God and Greyhound It's Gone
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Old 07-30-2014, 12:33 PM   #14
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A short 1/8" tube doesn't sound like a cap tube, typically you expect to see no less than 3 feet or so in length.

Can you take some pictures of the system and post them?
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Old 07-30-2014, 07:01 PM   #15
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IF this comes through: The unit is sitting on a board on some plastic sawhorses. The 1/8" tube runs horizontal to the bottom of the unit, goes through a black rubber isolation damper then turns upwards on the right hand side in front of the wiring bundle. There is a 3/8" tube that comes from the bottom of the condenser that turns straight up and appears to be the factory charging tube. The 1/8" tube is soldered into this 3/8" tube then goes somewhere into the evaporator. The overall length of this 1/8" tube may be around 24". As I said- -these RV units are something unto themselves. Thanks for the help
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