Questions about Air Conditioning

bauble

Registered User
Due to a problem with my radiator fan, I've lost most of the R12 in my AC system. My regular mechanic thinks it would be more cost-effective to upgrade to R134a rather than charge the system again (it's had a small leak for a while that required charging every year or two). I'm ok with that idea, but I would like to know about doing it myself: on another forum (non-car or SC related), one of the posters said that it isn't a big job, once the R12 is vacuumed out. Great!, thinks I, and head out to buy a retrofit kit. Then I'm told, after calling a local shop, that the compressor probably won't be able to handle the R134 (the guy I talked to said that R134 runs at 2x the pressure) and that the front seals will probably blow if I don't change the compressor.

So here's the questions:

1. Do I need to change the compressor ?

2. If I *do* need to change the compressor, what type/model do I need to get ?

3. (not really as relevant): Doesn't the compressor determine how much pressure the coolant is under ? I don't understand how changing the fluid will change the amount of pressure (which is not to say that I don't believe it could be that way, but it doesn't make sense to me).
 
It is not that difficult if you have some basic ac tools. My day job is manufacturing ac systems for the construction industry. The two big things between r134a and r12 is the oil type. You need to get out all of the r12 oil in the system, which means in the evaporator, condenser, and accumulator. The accumulator you well just replace along with the orifice tube. These are normally sold as kits. The other mane difference is the operating pressure; it is only slightly higher then r12. The molecule size of r134a is smaller so that is why they say to replace all of the “o” rings and seals in the compressor. The compressor is changed due too the different oil that is used for r134a and the seals.

If you have a place suck out the r12 have them flush the system too.
Then all you need to do is replace the accumulator, orifice tube, and compressor. All of these can be bought at any major parts store.
After the new parts are in you need to pull a vacuum on the system to check for leeks and also get all the air and moister out of the system.
They make retro fill kits that have r134a and the right amount of oil in the can plus the fittings to screw on the r12 ports to make them into r134a ports.
You will only need about 85% of the charge amount listed for the r12.
A rebuilt compressor will start at about $240, accumulator is around $45, r134a retro fill kit $35, and orifice tube $3.

Hope this helps
 
bauble said:
So here's the questions:

1. Do I need to change the compressor ?
Not if yours was working OK. If your concerned about the additional stress from using r134a, stick with R12. I wouldn't however, change out the compressor justto swap refrigerants.. whats the point of that?
bauble said:
2. If I *do* need to change the compressor, what type/model do I need to get ?
Most tbirds used the model FS10 or FX15.. FS10 seems to be the more prevelant.
bauble said:
3. (not really as relevant): Doesn't the compressor determine how much pressure the coolant is under ? I don't understand how changing the fluid will change the amount of pressure (which is not to say that I don't believe it could be that way, but it doesn't make sense to me).
Its not a fluid in the liquid sense. The refrigerant is a gas and a liquid a various points in the A/C lines. The only thing the compressor does is pumps the gas form into the condenser. The amount of pressure is determined by the amount of refrigerant (the charge) and the sizes of the condenser and orifice tube. For r134a to produce the same heat drop, that pressure ends up being about 1.5x as high as what R12 develops. :cool:
 
Stick with R-12

I just had mine re-charged and it only took 0.75 lbs @ $40/lb plus $25 labor. The guy who did it said he is constantly converting systems back to R-12 due to poor performance.
 
$40/lb??

clickster34 said:
I just had mine re-charged and it only took 0.75 lbs @ $40/lb plus $25 labor. The guy who did it said he is constantly converting systems back to R-12 due to poor performance.

Where did you find that for only $40/lb???? That's what thought it should cost, but I've been told that it's $200/lb when I called a few shops for a quote. One shop even tossed my keys back at me when I said I wanted the compressor tested (it wound up needing to be replaced) and the system recharged with R-12. I was told it's $200-300 per pound (I'd need ~2lbs), it's only made in mexico now, and good luck finding it!
 
clickster34 said:
I just had mine re-charged and it only took 0.75 lbs @ $40/lb plus $25 labor. The guy who did it said he is constantly converting systems back to R-12 due to poor performance.
Thats not unusual. 2 things are rather critical.. a more efficient condenser (all make of car with original R12) and a properly sized orifice tube. Not many people have any ideas which size O tube will work best, but its not always the stock size. If the retrofitter doesn't address these, chances are good the results won't be great.
 
redknight said:
Where did you find that for only $40/lb???? That's what thought it should cost, but I've been told that it's $200/lb when I called a few shops for a quote. One shop even tossed my keys back at me when I said I wanted the compressor tested (it wound up needing to be replaced) and the system recharged with R-12. I was told it's $200-300 per pound (I'd need ~2lbs), it's only made in mexico now, and good luck finding it!


im in mexico.........let me see how much is down here. and ill tell you tomorrow
 
I'm in Findlay, Ohio

redknight said:
Where did you find that for only $40/lb???? That's what thought it should cost, but I've been told that it's $200/lb when I called a few shops for a quote. One shop even tossed my keys back at me when I said I wanted the compressor tested (it wound up needing to be replaced) and the system recharged with R-12. I was told it's $200-300 per pound (I'd need ~2lbs), it's only made in mexico now, and good luck finding it!

It's just a small local owned shop that did it for me, the only other place that I found to service R-12 was charging $90/lb plus labor. I guess there are a few people around that are willing to work for less than 300% profit. They also said that it is a common misconception that R-12 won't be available anymore. They have no problem getting it as long as they are certified and still have customers wanting it. If you can get it for a good price, I think just recharging is the way to go. @ $200-300/lb, it sounds like you would be better off building an R-134a sytem with new everything and a more efficient condenser. If you go that route you can always just recharge your system yourself in the future, or at least until they make R-134a illegal to sell to consumers. I was quoted around $400 for a R-134a conversion and the only new part was the dryer. I have seen a few compressor/dryer/retrofit kit for the SC on ebay for a reasonable price.
 
i can get it for 25dlls/lb +shipping.

altough i dont know if can ship it.

if someone can do a lil research on that it will be great.

btw i would ship it from california.
 
Last edited:
R-134a Conversion

bauble said:
Due to a problem with my radiator fan, I've lost most of the R12 in my AC system. My regular mechanic thinks it would be more cost-effective to upgrade to R134a rather than charge the system again (it's had a small leak for a while that required charging every year or two). I'm ok with that idea, but I would like to know about doing it myself: on another forum (non-car or SC related), one of the posters said that it isn't a big job, once the R12 is vacuumed out. Great!, thinks I, and head out to buy a retrofit kit. Then I'm told, after calling a local shop, that the compressor probably won't be able to handle the R134 (the guy I talked to said that R134 runs at 2x the pressure) and that the front seals will probably blow if I don't change the compressor.

So here's the questions:

1. Do I need to change the compressor ?

2. If I *do* need to change the compressor, what type/model do I need to get ?

3. (not really as relevant): Doesn't the compressor determine how much pressure the coolant is under ? I don't understand how changing the fluid will change the amount of pressure (which is not to say that I don't believe it could be that way, but it doesn't make sense to me).

I just converted both of my '89's. All I did was install the new-style fittings, pull a vacuum on the system, and blow it up to spec's with R-134a using one of those parts store kits. The systems work fine. Not quite as cold as a new-condition R-12 system, or a "from the factory" R-134a system, but quite acceptable. By the way, I'm located in south Texas, so it's not like it doesn't get hot here.

If they end up crapping out, so what. I'll just have to replace the parts that others have said must be replaced from the start. Nothing lost.

JD
 
txsc said:
I just converted both of my '89's. All I did was install the new-style fittings, pull a vacuum on the system, and blow it up to spec's with R-134a using one of those parts store kits. The systems work fine. Not quite as cold as a new-condition R-12 system, or a "from the factory" R-134a system, but quite acceptable. By the way, I'm located in south Texas, so it's not like it doesn't get hot here.

If they end up crapping out, so what. I'll just have to replace the parts that others have said must be replaced from the start. Nothing lost.

JD
That's pretty good. Especially pulling a vaccuum and not waiting for a leak to take out the compressor. If you wait till they break, it takes a lot more work and $ to fix up.

With a new serpentine condenser, a blue Otube, and a slight adjustment of the pressure switch cycling point, you can get as cold as R12 even in the fun Texas heat..

I used to gripe about it compared to the R12, but this summer, I hooked up the guages, made 1 tweak of the pressure switch, and its been working great ever since. :cool: I actually turn it off at times.
 
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