R-12- conversion or top-off?

I've got a '92 that has very weak AC. I checked the sight glass and I get a steady stream of bubbles passing though, but I have no idea how to test the pressures on the high and low sides (I did my searching ).

So the questions are-

1- how do I test the referigerant pressures?

2- How do I add more freon?

3- How do I know when to stop adding freon?

I plan to simply get my EPA cirtificate and buy freon, it's MUCH cheaper than the $350 I was quoted to convert to R-134a, and should get me by for several years, this is a very slow leak and topping off will be sfficient (I think).

Any other comments are welcome as well.

There is a save drop in for r12 called Freeze 12.
http://autorefrigerants.com/

Since you're asking these basic questions, I'm going to go out on a limb and say you don't know what you're doing with A/C, so don't mess with R-12.

You can buy a kit at AutoZone for like 50 bucks or maybe even less to convert an old R-12 system to the new R-134a refrigerant. HOWEVER, since you still have some old R-12 in the system, you cannot just use this kit and expect a proper working A/C system. The refrigerant has to be identified as uncontaminated R-12 (not propane or anything), then the system has to be properly evacuated, vacuumed down, then converted to R-134a and filled.

My advice to you is to let the shop handle the conversion. By the time you get the cert, buy the freon and equipment you'll need to work on it, you'll have spent probably well over the $350 you were quoted.

I have the same symptoms with my a/c in my 93 and I've been looking for these answers also...where is this little window at?

andrew2516 said:

I have the same symptoms with my a/c in my 93 and I've been looking for these answers also...where is this little window at?

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Not all systems have it.

I just went through that retro-fit thing and lucky for me my mechanic friend saved me from myself. I had the kit from Auto Zone, and then found out that if you don't change everything else on an old system you are just asking for trouble. Auto zone neglected to tell me the whole story. I went ahead and had my friend buy 2 cans of r12 and was going to put it in for me, but we found that it didn't actually need it. We think maybe it's the thermostat instead letting it freeze up. Just my input, good luck. Gigage

anony91xj said:

Since you're asking these basic questions, I'm going to go out on a limb and say you don't know what you're doing with A/C

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Correct. Completely clueless.

anony91xj said:

You can buy a kit at AutoZone for like 50 bucks or maybe even less to convert an old R-12 system to the new R-134a refrigerant. HOWEVER, since you still have some old R-12 in the system, you cannot just use this kit and expect a proper working A/C system. The refrigerant has to be identified as uncontaminated R-12 (not propane or anything), then the system has to be properly evacuated, vacuumed down, then converted to R-134a and filled.

My advice to you is to let the shop handle the conversion. By the time you get the cert, buy the freon and equipment you'll need to work on it, you'll have spent probably well over the $350 you were quoted.

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I have considered this quite a bit, and pretty much made my decision to try it myself, some for the learning experience, and also because I'm cheap (just paid $1000 for 3 credits tuition for the summer!)

The certification is about $20, no biggie. I order a few cans of Freon online, dump it in and away I go, only cool this time. I think total cost is about $50-60.

the other option is to have the shop do it for $350, which will also cost a 1/2 day at work sometime next week, so that puts me at closer to $450. This is for the complete conversion with new orifices and drier for R-134a.

OK, here's the "rest of the story".

I purchased some Freeze-12 based on some reports I read through some online searching that said it was a direct replacement. It got here today.

The instructions said to replace the drier and orifice with parts compatible with R-134a, evacuate the system, yada-yada. I was sure my searching had led me to a product that would replace the R-12, so I got mad, kicked the dog, taught the kids to say @$& and *&^$, then researched getting a 609 certificate to buy Freon on Ebay....then came here and posted.

On the website, Freeze-12 says it is a replacement for R-12 without anything else needing to be done, so there is a difference in the written instruction they send. On the can (didn't bother to read it before) the instructions are to evacuate the R-12 and replace with Freeze-12.

so....

1- anyone ever dumped a can in without evacuating the r-12? Any risk in it?

2- Where do I dump it in?

3- How do I know when to stop?

Thanks again-
Shane (hot in Utah)

Add Freeze-12 to the low pressure port with the can upside down intill there are no more bubbles in the sight glass.
If you don't have a sight glass hold your hand on the large tube comming out of the evap and fill until it starts getting cold.

Beer can cold?

Snoop around here first: http://www.autoacforum.com/

If you have bubbles in the sight glass of the reciever/drier, you have a leak somewhere.

A 609 Certification doesn't teach you a thing, other than the harm that CFC's do to the ozone, and R-12 regulations.

If you don't know what you are doing, you can seriously hurt yourself. A can of r-12 is potentially as dangerous as half a stick of dynamite. Do yourself a favor and buy a book. The Haynes A/C manual does a pretty good job actually.

To do it right, you'll need a real set of guages, and a vacuum pump (the air powered ones aren't all that great, and won't do the job right). I know that people have just dumped some in, and it cooled O.K. without buying the right tools, but I'm sure you can rebuild an engine with a pair of pliers too. I like having the right tools for the job.

Legally, you can't just dump in a can of R-12. You have to recover the old R-12, test the system for leaks, repair the leaks, and then fill with new, or recycled (not reclaimed) R-12. If you get caught not doing it by the book, it's a $15,000 fine, and $10,000 of that goes to the person that turned you in.

It isn't hard to retrofit an XJ to R-134A. They actually cool pretty good with it too.

You need to replace all of the O-rings, flush the system to remove ALL of the old oil (even in the compressor), a new reciever drier, install a high pressure cutoff switch, new R-134a fittings, vacuum it down to remove all of the moisture, add the new R-134a specific oil, and THEN recharge it. You are looking for a high side reading of 2 - 2.5 times the ambient temperature in PSI. If it's 90 degrees outside, you are looking for a high side reading of 180 - 225 PSI (90 X 2 = 180, 90 X 2.5 = 225 PSI) Get the high side up to 180 PSI, stick a thermometer in the center vent, turn the blower on high, let the temp equalize and adjust the pressure to get the coldest reading. Let the temp equalize after each adjustment. Don't go over 2.5 times ambient, the compressor won't last long. They weren't designed to run at really high pressures. Mine gets to around 45 degrees at 90 degrees outside temp. The heater valves don't seal well on XJ's either, so disconnecting the heater hoses to the heater core helps quite a bit too. Older XJ's use an "H" valve instead of an orifice tube. The H valve relies "mostly" on temperature so it doesn't really know if it's R-12, or R134A, and it's pretty forgiving on over/under charging of the system.

Hope it helps.

Thanks all, I put one can of Freeze-12 into the low side and it's cooling quite well again at 85* outside. I still have two cans left in case there is a problem. I may try bypassing the heater core to keep heat out, that sounds like a good idea until I get close to overheating somewhere and can't get rid of heat.

SCW said:

Thanks all, I put one can of Freeze-12 into the low side and it's cooling quite well again at 85* outside. I still have two cans left in case there is a problem. I may try bypassing the heater core to keep heat out, that sounds like a good idea until I get close to overheating somewhere and can't get rid of heat.

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Your blend door should cut off the heater core when you've got the temp switch set all the way to cold.