Well, I was hoping this was going to be quick & cheap. Guess not as I can see I'm gonna have to start buying other stuff just to get the Freeze 12 into the system.

How can I tell which is the low pressure & high pressure ports?

If there are two different size lines, the smaller one is usually the low side.

Clay

you sure about that, I just converted mine to 134 and my low side is the large line. Also I found out thanks to Glenn the clutch will not engage if the system is out or very low, due to the low pressure switch. So i have now removed my temporary hot wire to the clutch and everything works great. The low pressure adaptor will only fit on the low side anyway. <img src="/forums/images/graemlins/kewl.gif" alt="" />

When you converted yours, did you evacuate the old freon? Just wondering what would happen if, since my R12 is gone, can I just retrofit for R134 & put it in? I haven't had much luck finding a way to put my R12 substitute (Freeze 12) in. I went to 5 places today. They either don't do R12 anymore or will not take customer's freon & put it in.

I could be wrong, it's been known to happen on occasion. I'm offering the best advice I can but the fact is that I haven't even lifted the hood on mine to see.

As far as converting, you really should evacuate and vacuum the system to make sure there isn't any left. There is likely still some in there somewhere.

BTW, I replaced a set of a/c hoses on a truck (chevy) the other day. I evacuated the system, then I vacuumed it for 3 mintutes. Then I watched to see if it would hold vacuum. It held 28" Hg for 2 full minutes. I disconnected teh machine and parked the truck, waiting for the work to get sold. When I brought it back in 1 1/2 hours later and pulled the bolt out of the compressor, yellow/green foamy oil came out under pressure. I had even turned the compressor by hand with the machine on it and no new pressure appeared.

So, yes. You need to vacuum the system before converting.

Clay

Charlie, I tried that on mine and no go. Once air gets in the system from a leak, or from having the system open, then you'll get too much pressure for the gas to enter...or it will blow a hole somewhere else.

You'll need to vac.

Just a word of caution here - too much stop leak and even too much of the coolant with the test dye dye in it can completely clog up your A/C system. At least that's what happened on the Grand Cherokee I had a few years ago. I was having problems with its A/C and tried to locate where the leak was by using the test dye. The A/C stopped working altogether & when I had a pro look at it before I sold the truck he said that one of the lines was completely clogged up from the dye.

Just an FYI!

Your LOW side port is the standard 1/4" A/C hose connection. The High side IS the smaller one, 3/16". This is done so that someone doesn't use a can type recharge set-up with its normal, single 1/4" short hose hanging from it and hook it up to the high side, blowing the small 12 oz can out of their hand[and taking some body parts with it] <img src="/forums/images/graemlins/shiner.gif" alt="" /> <img src="/forums/images/graemlins/shiner.gif" alt="" /> <img src="/forums/images/graemlins/shiner.gif" alt="" />
To get good results out of your A/C system, you DO need to have a vacuum pulled down on the system ONCE you fix the leak[s]. This removes any moisture left in the system from whatever leak you once had. Water will freeze up in certain parts of the system, blocking freon flow if you've left enough of it in there. Also, as always, alloy parts/lines corrode from water in your A/C system and any steel parts rust. Both are bad for the A/C system.
If your Gen 2 Monty is like most Gen 2 Monteros, your leak is the evaporator inside the dash, basically behind the glovebox. Not a hard job at all to change out if that's what's leaking on yours.'
Another sneaky spot is the glass viewing port at the top of the receiver/drier. I've seen freon slowly leak from around the glass itself. You need the small section of metal line that comes with the new glass 'window' to fix this one.
Back to your system, and anyone elses. Just adding dye or some type of stop leak won't do much except for a lighter load on your wallet. Nether will cure a leak, only a new part will do that. The reason is that A/C systems run at much higher pressures than say a coolant system where people also try using "stop leak" like for a head gasket that's weeping.
The only time you have low system pressure in an A/C that's working correctly is when it's operating, and only on the Low side, usually well under 50 psi depending on R-12 or R-134. Once you shut the system off, the low side pressure climbs quickly up to ambient temps/pressure, usually close to the actual temp of the moment with R-12. So you're at 70, 80, 90 psi as your LOW before you know it.
High sides run all the way up to 450psi[R-134] as a norm in a hot climate.
Fix your car like you want, just don't expect any short cuts to take care of a leaking A/C system.
Let me know if you want more help

guess i got lucky, my compressor was empty from my raider, never really understood the vacumn thing until now. Best bet is to vacumn the system at least like the guys said and go with r134 and get away from r12. I think you are also recommended to replace acumulator or dryer one of the two.

Well Houston, I still have my A/C problem but thanks for the extensive response. Good info there.

Just to recap, I only need this to work for a couple months. Thru August at the most. If I have to put a can of FREEZE 12 in once a month so be it.

I had the 3-10 oz cans of Freeze 12 put in today. A/C started cold but got warm after awhile. Mechanic thinks there is a blockage somewhere in the system. Also, they saw dampness on the compressor which they think is oil leaking from the A.C. At least the compressor is coming on. Just have to fix or slow the leak.

Is the low side the valve that points up or the valve that points towards the radiator?